Microbiology Tortora/ third lecture exam

What does ID50 stand for?

(Infectious Dose) The dose necessary to INFECT 50% of the test organisms

What does LD50 stand for?

(Lethal Dose) The dose necessary to KILL 50% of the test organisms

sarcoma

(cancer of connective tissue) can be similarly transmitted or transferred from infected sources

Virus-induced adenocarcinomas

(cancers of glandular epithelial tissue) in mice were discovered in 1936. At that time, it was clearly shown that mouse mammary gland tumors are transmitted from mother to offspring through the mother's milk.

virulence

(degree of pathogenicity), the number of infecting microorganisms, and the resistance of the host.

pathogens

(disease-causing microorganisms).

Influenza

(some types) Influenzavirus Reservoir Swine birds Direct contact

Discuss the relationship between DNA- and RNA-containing viruses and cancer

*~ 10% of cancers are caused by viruses Several DNA viruses are retroviruses and oncogenic. The genetic material of oncogenic viruses become integrated into the host cells DNA. DNA viruses include HPV and Hep. B. Among the RNA viruses only the retroviruses seem to oncogenic. HTLV-1&2 have been found to cause cancer. *Activated oncogenes transform normal cells into cancerous cells *Transformed cells have increased growth, loss of contact inhibition, tumor-specific transplant antigens, and T antigens *The genetic material of oncogenic viruses becomes integrated into the host cell's DNA

Causes of UTI

-E. coli major culprit causing 80-85% of cases -Remaining cases caused by staphylococcus

Why are viruses difficult to control?

-changes due to viral replication -inside our cells -have to wait for the antibodies to show

3 techniques to identify/detect viruses.

-needs to be seen by an electron microscope -reaction with antibodies (serological test) -Restriction Fragment Length Polumorphisms (RFLPs) and the polymerase chain reaction (PCR)

List ways that viruses are inhibited

-our bodies defenses -antiviral drugs that stop viruses at certain steps -interferons (antiviral proteins produced by human cells in response to the infection) -viral vaccines

CDC Category A

1) Bacillus antrhacisis - ANTHRAX 2) Clostridium botulinum toxin * (not zoonoses) 3) Yeshira pestis 4) Variola major - SMALLPOX (not zoonoses*) 5 Franicsella tularensis - TULARemIA

name the method of transmission of each of the following diseases: 1) malaria 2) tuberculosis 3) nosocomial infections 4) salmonellosis 5) streptococcal pharyngitis

1)female mosquito bite through the air from one person to another 2) through the air from one person to another 3) patients, hospital personnel, or visitors 4) 5) respiratory droplets or close contact

List 3 Theories of How Viruses Developed

1-Co-Evolution with more complex life forms 2-Escaped Gene Theory 3-Retrograde Evolution

Give 2 forms of Polio

1-Intestinal form 2-Paralytic Polio (Poliomyelitis: attacks neurons in the CNS)

List the steps of Lysogenic Viral Multiplication

1-Virus attaches to Host cell 2-Nucleic acid is transferred to Host cell 3-Virus & Host cell's Nucleic acids combine 4-Replication of combined Nucleic acid by Host cell 5-Host cell divides into 2 daughter cells (Temperate phages)

Dependent on CHEMICAL ATTRACTION and GLYCOPROTEIN SPIKES (receptors)

1. DIRECT ENTRY (VIRAL DNA into cell) 2. MEMBRANE FUSION (CAPSID into cell) 3. ENDOCYTOSIS (WHOLE VIRUS into cell)

What are the three (3) factors that determine the MALIGNANCY of a certain type of cancer?

1. How easily BLOOD VESSELS can go around tumor 2. How INVASIVE cancer is 3. LEVEL OF DIFFERENTIATION from human cells.

Descibe how animal viruses are cultured.

1. Living Animals: Most experiments to study the immune system's response to viral infections must also be performed in virally infected live animals. Animal inoculation may be used as a diagnostic procedure for identifying and isolating a virus from a clinical specimen. 2.Embryonated Eggs: this can be a fairly convenient and inexpensive form of host for many animal viruses. A hole is drilled in the shell of the embryonated egg, and a viral suspension or suspected virus-containing tissue is injected into the fluid of the egg. There are several membranes in an egg, and the virus is injected near the one most appropriate for its growth 3. Cell Cultures:Cell culture lines are started by treating a slice of animal tissue with enzymes that separate the individual cells.These cells are suspended in a solution that provides the osmotic pressure, nutrients, and growth factors needed for the cells to grow. Normal cells tend to adhere to the glass or plastic container and reproduce to form a monolayer.

What environmental factors contribute to the activation of oncogenes?

1. UV light 2. Radiation 3. Carcinogens 4. Viruses

Describe how animal viruses are cultured (3 methods)

1. Using living animals; diagnosing Immunol infections, via animal inoculation. after animal is inoculated w/ specimen, animal is observed or killed for examination :(. AID's does not work with this method. 2. Embryonic eggs; depends on if the virus will grow within the embryonic egg. Viral suspension is injected into the egg. Viral growth is indicated by death of the embryo, cell damage, or formation of pocks/ lesions. 3. Cell structures; preferred, consist of cells grown in culture media in the lab. Similar to working with bacteria. First, you treat a slice of animal tissue with enzymes that separate individual cells. Next, you suspend the cells in a solution that provides nutrients and osmotic pressure. When virus infects the cells, the cells deteriorate.

Describe the LYTIC cycle of replication for viruses.

1. Virus ATTACHES to host cell 2. Virus' genetic material or the genetic material and the capsid ENTER host cell 3. Enzymes of virus BREAK DOWN DNA of host and SYNTHESIZE VIRAL PROTEINS 4. New viral particles ASSEMBLE to become VIRIONS 5. Virions RELEASE themselves from host by bursting host or by BUDDING.

Describe the LYSOGENIC cycle.

1. Virus enters the host cell and INTEGRATES its DNA with host's DNA. 2. LATENT virus stays DORMANT and waits in cytoplasmic membrane or DNA of host cell. 3. Host cell undergoes MITOSIS so that ALL daughter cells will have viral DNA. 4. Viruses wait for OPPORTUNE time to be TRIGGERED to wake up and be active.* *Basically whenever human's immune system is shortly compromised.

What are the four (4) types of viral genetic material?

1. double-stranded DNA (dsDNA) 2. single-stranded DNA (ssDNA) 3. dsRNA 4. ssRNA

How can opportunistic pathogens cause infections?

1. introduction into sterile tissues 2. infection of persons w/ underlying conditions that increase susceptibility 3. infection in immunocompromised patients

staphylococcal toxin

2nd leading cause of food sickness

E. coli produces ___________ genes in 40 minutes

3000

vagina pH

4

E. coli + T4 produce ________________genes in 40 minutes

600,000

Which technique is used to separate protein fragments based on size? A.polyacrylamide gel electrophoresis B.Southern blot C.agarose gel electrophoresis D.polymerase chain reaction

A

Southern blot

A Southern blot is a method used in molecular biology for detection of a specific DNA sequence in DNA samples. Southern blotting combines transfer of electrophoresis-separated DNA fragments to a filter membrane and subsequent fragment detection by probe hybridization.

When a virus is outside of the cell, what is it called?

A VIRION.

What is a Virion composed of?

A Virion is composed of a Nucleocapsid

spikes

A carbohydrate -protein complex that projects the surface of viruses

What is Agarose Gel Electrophoresis?

A common laboratory method for separating DNA fragments of different sizes. Electric field is passed through agarose gel in an electrophoresis chamber DNA samples loaded on one end migrate to the other during the process

The Spread of Infection Reservoirs of Infection

A continual source of infection is called a reservoir of infection. People who have a disease or are carriers of pathogenic microorganisms are human reservoirs of infection. Zoonoses are diseases that affect wild and domestic animals and can be transmitted to humans. Some pathogenic microorganisms grow in nonliving reservoirs, such as soil and water.

Helical virus

A cylindrical Helical array of capsid proteins wrapped around a Helical filament of Nucleic acid. Ex. Rabies

how oncogenic viruses operate

A defining feature of all oncogenic viruses is that their genetic material integrates into the host cell's DNA and replicates along with the host cell's chromosome,similar to to the phenomenon of lysogeny in bacteria, and it can alter the host cell's characteristics in the same way.

deadly mushrooms

A few mushrooms produce fungal toxins called mycotoxins. Examples are phalloidin and amanitin, produced by Amanita phalloides (A-man-ī-tah fal-LOI-dēz), commonly known as the deathcap. These neurotoxins are so potent that ingestion of the Amanita mushroom may result in death.

oncogene

A gene that in certain circumstances can transform a cell into a tumor cell,Oncogenes can be activated to abnormal functioning by a variety of agents, including mutagenic chemicals, high-energy radiation, and viruses.

Experimental epidemiology

A group of infected individuals is selected and divided randomly so that some receive the drug and others receive a placebo, a substance that has no effect.

Latent Viral Infections

A latent viral infection is one in which the virus remains in the host cell for long periods without producing an infection. Examples are cold sores and shingles.

Extent of Host Involvement

A local infection affects a small area of the body; a systemic infection is spread throughout the body via the circulatory system. A primary infection is an acute infection that causes the initial illness. A secondary infection can occur after the host is weakened from a primary infection. An inapparent, or subclinical, infection does not cause any signs of disease in the host.

Polyhedral virus

A many-sided virus; most commom is Icosahedral. Ex. Polio

Classifying Infectious Diseases

A patient may exhibit symptoms (subjective changes in body functions) and signs (measurable changes), which a physician uses to make a diagnosis (identification of the disease). A specific group of symptoms or signs that always accompanies a specific disease is called a syndrome. Communicable diseases are transmitted directly or indirectly from one host to another. A contagious disease is a very communicable disease that is capable of spreading easily and rapidly from one person to another. Noncommunicable diseases are caused by microorganisms that normally grow outside the human body and are not transmitted from one host to another.

Predisposing Factors

A predisposing factor is one that makes the body more susceptible to disease or alters the course of a disease. Examples include gender, climate, age, fatigue, and inadequate nutrition.

proteases

A protease (also called a peptidase or proteinase) is any enzyme that performs proteolysis; protein catabolism by hydrolysis of peptide bonds. Proteases have evolved multiple times, and different classes of protease can perform the same reaction by completely different catalytic mechanisms.

serovar

A serotype or serovar is a distinct variation within a species of bacteria or virus or among immune cells of different individuals. These microorganisms, viruses, or cells are classified together based on their cell surface antigens, allowing the epidemiologic classification of organisms to the sub-species level.

syndrome

A specific group of symptoms or signs may always accompany a particular disease; such a group is called a syndrome

In the symbiotic relationship called commensalism

A symbiotic relationship in which two organisms live in association and one is benefited while the other is neither benefited or harmed

vector

A vector is a DNA molecule that transports foreign DNA into a cell The gene of interest is inserted into the vector DNA in vitro the vector is a plasmid. This recombinant vector DNA is taken up by a cell such as a bacterium, where it can multiply The cell containing the recombinant vector is then grown in culture to form a clone

Viral Structure

A virion is a complete, fully developed viral particle composed of nucleic acid surrounded by a coat.

How do prions differ from viruses?

A virus is genetic material (either DNA or RNA, depending on the virus) wrapped in a protein coat. Once inside a cell, it can hijack the cell to make more copies of itself. A prion doesn't contain genes. It's a protein and can induce other protein molecules to reform in its image.

Diphtheria,Corynebacterium diphtheriae

A-B exotoxin Cytotoxin inhibits protein synthesis, especially in nerve, heart, and kidney cells.

Tetanus ,Clostridium tetani

A-B exotoxin,Neurotoxin blocks nerve impulses to muscle relaxation pathway; results in uncontrollable muscle contractions.

Human carriers spread

AIDS, diphtheria, typhoid fever, hepatitis, gonorrhea, amebic dysentery, and streptococcal infections.

Pathogenicity

Ability to cause disease

Toxigenicity

Ability to produce a toxin

zoonoses

About 150 zoonoses are known. The transmission of zoo- noses to humans can occur via one of many routes: by direct contact with infected animals; by direct contact with domestic pet waste (such as cleaning a litter box or bird cage); by contamination of food and water; by air from contaminated hides, fur, or feathers; by consuming infected animal products; or by insect vectors (insects that transmit pathogens).

Are viruses unicellular, multicellular, both or acellular? Why?

Acellular; No ribosomes, no cell membrane, no cytoplasm

Adaptive immunity

Adaptive immunity refers to a specific defensive response of the body to an infection or to antigens

Proteins in the cell wall can facilitate what?

Adherence

Algae

Alexandrium, are important medically because they produce a neurotoxin called saxitoxin people who eat the mollusks develop paralytic shellfish poisoning, with symptoms similar to botulism. Public health agencies frequently prohibit human consumption of mollusks during red tides

Transmission of plant viruses by insects can occur from viruses associated with insect mouth parts. viruses circulating but not multiplying in the insect's body. viruses that multiply within the body of the insect. All of the above

All of the above

Once inside the host cell, phage DNA is replicated. is transcribed. may get degraded by bacterial nucleases. All of the choices are correct

All of the choices are correct.

Plant viruses may be transmitted by worms. contaminated seeds. humans. insects. All of the choices are correct.

All of the choices are correct.

Regarding phage replication, the majority of phages are temperate. when integrated into host DNA, the phage DNA is called a prophage. lambda is a good example of a temperate phage. All of the choices are correct.

All of the choices are correct.

Spongiform encephalopathy occurs in humans. cattle. sheep. All of the choices are correct.

All of the choices are correct.

Latent Viral Infections

All of the human herpesviruses Simplexvirus,chickenpox virus (Varicellovirus),

Stanley Prusiner

American neurobiologist Stanley Prusiner proposed that infectious proteins caused a neurological disease in sheep called scrapie.

What is agarose gel?

An Agarose gel is made of seaweed which solidifies to form a gel slab on cooling to room temperature

Disease

An abnormal state in which part or all of the body is not properly adjusted or is incapable or is incapable of normal functions; any change from a sate of health.More microorganisms are introduced to the newborn's body from the environment when breathing begins and feeding starts. After birth, E. coli and other bacteria acquired from foods begin to inhabit the large intestine

restriction enzymes

An enzyme that cuts double stranded DNA at specific sites between nucleotide

Prion

An infectious agent consisting of a self replicating protein with no detectable nucleic acids.A proteinaceous infectious particle.A prion doesn't contain genes. It's a protein and can induce other protein molecules to reform in its image.

Multiplication of Animal Viruses

Animal viruses attach to the plasma membrane of the host cell. Entry occurs by receptor-mediated endocytosis or fusion. Animal viruses are uncoated by viral or host cell enzymes. The DNA of most DNA viruses is released into the nucleus of the host cell. Transcription of viral DNA and translation produce viral DNA and, later, capsid proteins. Capsid proteins are synthesized in the cytoplasm of the host cell. DNA viruses include Adenoviridae, Poxviridae, Herpesviridae, Papovaviridae, and Hepadnaviridae. Multiplication of RNA viruses occurs in the cytoplasm of the host cell. RNA-dependent RNA polymerase synthesizes a double-stranded RNA. Picornaviridae + strand RNA acts as mRNA and directs the synthesis of RNA-dependent RNA polymerase. Togaviridae + strand RNA acts as a template for RNA-dependent RNA polymerase, and mRNA is transcribed from a new − RNA strand. Rhabdoviridae − strand RNA is a template for viral RNA-dependent RNA polymerase, which transcribes mRNA. Reoviridae are digested in host cell cytoplasm to release mRNA for viral biosynthesis. Retroviridae reverse transcriptase (RNA-dependent DNA polymerase) transcribes DNA from RNA. After assembly, viruses are released. One method of release (and envelope formation) is budding. Nonenveloped viruses are released through ruptures in the host cell membrane

Arthropod Vectors and the Diseases They Transmit

Anopheles Plasmodium spp. (protozoan)(mosquito),malaria African trypanosomiasis, Trypanosoma brucei gambiense and T. b. rhodesiense (protozoan), Glossina (tsetse fly)

conjugation

Another mechanism by which genetic material is transferred from one bacterium to another

Some antibiotics activate phage genes. MRSA releasing Panton-Valentine leukocidin causes a life-threatening disease. Why can this happen following antibiotic treatment?

Antibiotics treatement of S.Aureus can avtivate Phage genes that encode for Panton-Valentine leukocidin

Antitoxins

Antitoxins (antibodies) are produced by the host body and neutralize toxins

Vectors

Arthropods are the most important group of disease vectors— animals that carry pathogens from one host to another.Houseflies, for instance, can transfer the pathogens of typhoid fever and bacillary dysentery (shigellosis) from the feces of infected people to food.

Control of Healthcare-Associated Infections (HAIs)

Aseptic techniques can prevent HAIs. Hospital infection control staff members are responsible for overseeing the proper cleaning, storage, and handling of equipment and supplies.

What are the steps of the lysogenic cycle?

Attachment, Entry, Uncoat, Biosynthesis, Release

What are the steps of the lytic cycle?

Attachment, Penetration, Biosynthesis, Maturation and Release

A virus with RNA-dependent RNA polymerase A.synthesizes DNA from an RNA template. B.synthesizes double-stranded RNA from an RNA template. C.synthesizes double-stranded RNA from a DNA template. D.transcribes mRNA from DNA. E.none of the above

B

All of the following techniques involve hybridization between single-stranded nucleic acid molecules except: A.Southern blot analysis B.RFLP analysis C.northern blot analysis D.microarray analysis

B

An example of lysogeny in animals could be A.slow viral infections. B.latent viral infections. C.T-even bacteriophages. D.infections resulting in cell death. E.none of the above

B

Horizontal gene transfer

Bacteria can pass their genes laterally not only to their offspring but to other microbes of the same generation

Using the Host's Nutrients: Siderophores

Bacteria get iron from the host using siderophores

An example of how PFUs are counted is:

Bacteria is placed on a Media plate, a virus is dropped into the plate, incubated; you're looking for clear area where Bacteria went through the Lytic phase

How do bacteria reach the kidney from the bladder?

Bacteria possess adhesion molecules (p-fimbriae) which bind to uroepithelial cells. The adhesion also promotes an inflammatory response. There also is usually an element of vesicoureteral or intrarenal reflux.

Opa

Bacteria that produce Opa form opaque colonies on culture media.bacterial outer memebrane protein

Lysis of Host cell

Bacterial cell bursts, and Virulent Virions are released to infect other Host cells

fever (pyrogenic response) caused by endotoxins

Bacterial cell death caused by lysis or antibiotics can also produce fever by this mechanism. Both aspirin and acetaminophen reduce fever by inhibiting the synthesis of prostaglandins

Viruses are easiest to grow in ________ ________

Bacterial cells

How do bacteriophages get nucleotides and amino acids if they don't have any metabolic enzymes?

Bacteriophages propagate themselves by hijacking the metabolic enzymes of bacteria they infect and using amino acids and nucleotides etc already present in the cytoplasm.

retroviral enzyme

Because mRNA cannot be cloned directly, in the laboratory mRNA must be used as a template by the retroviral enzyme reverse transcriptase to make complementary DNA (cDNA)

Why are cancer cells immortal?

Because they shut genes that kill them OR STOP APOPTOSIS

The term filterable viruses was coined by

Beijerinck.

biofilms

Biofilms represent another method of adherence and are important because they resist disinfectants and antibiotics.

A viral species is not defined on the basis of the disease symptoms it causes. The best example of this is A.polio. B.rabies. C.hepatitis. D.chickenpox and shingles. E.measles.

C

The molecule serving as mRNA can be incorporated in the newly synthesized virus capsids of all of the following except + strand RNA picornaviruses. + strand RNA togaviruses. − strand RNA rhabdoviruses. double-stranded RNA reoviruses. Rotavirus.

C

Which of the following statements is false ? A.Viruses contain DNA or RNA. B.The nucleic acid of a virus is surrounded by a protein coat. C.Viruses multiply inside living cells using viral mRNA, tRNA, and ribosomes. D.Viruses cause the synthesis of specialized infectious elements. E.Viruses multiply inside living cells.

C

Which of the following would be the first step in the biosynthesis of a virus with reverse transcriptase? A.A complementary strand of RNA must be synthesized. B.Double-stranded RNA must be synthesized. C.A complementary strand of DNA must be synthesized from an RNA template. D.A complementary strand of DNA must be synthesized from a DNA template. E.none of the above

C

Which technique uses restriction enzyme digestion followed by agarose gel electrophoresis to generate a banding pattern for comparison to another sample processed in the same way? A.qPCR B.RT-PCR C.RFLP D.454 sequencing

C

Following the idea of specificity with viruses, which human cells does HIV attack?

CD4+ lymphocytes

Gerstmann-Sträussler-Scheinker syndrome

CJD has been transmitted with transplanted nerve tissue and contaminated surgical instruments.

Give several examples of microbial antagonism

Candida albicans - held at bay by vagina pH and causes yeast infections and vaginitis. Escherichia coli - produces Vit K and Vit B in the intestines, prevents adherence of Salmonella and Shigella.

What structures make up a capsid?

Capsomeres

What causes virulence of S. pneumo?

Capsule's proteins.

Spike

Carbohydrates-protein complexes that project from the surface pf the envelope

Insects are used a lot as __________ for viruses in Genetic Engineering

Carriers

Define cytopathic effects and give five examples?

Cause the macromolecular synthesis to cease, cause cell's lysosomes to release enzymes and destroy cell, the production of an inclusion body, formation of a large multinucleate cell called a syncytium, change cell function without visually changing cell, production of interferons, antigenic variation, chromosomal changes, and loss of contact inhibition.

Define Escaped Gene Theory

Cells lost control of their genetic material, genes escaped, and became their own separate units

What are the two (2) types of PRIONS and how do they contrast?

Cellular PRP has an alpha-helix structure, which is NORMAL. Prion PRP has a beta-pleated sheets structure, which is INFECTIOUS. Also, prion PRP can change the alpha-helices of cellular PRP into beta-pleated sheets, making them unable to do their function.

Microorganisms in the Hospital

Certain normal microbiota are often responsible for HAIs when they are introduced into the body through such medical procedures as surgery and catheterization. Opportunistic bacteria are the most frequent causes of HAIs

Toxin

Chemicals that harm tissues or trigger host immune responses that cause damage

Some viruses can only be grown in a living organism. What organism is used most?

Chicken embyros

contagious diseases

Chickenpox and measles are also examples of contagious diseases, that is, diseases that are very communicable and capable of spreading easily and rapidly from one person to another.

What is the smallest Bacteria?

Chlamydia-1000 nm

Taxonomy of Viruses

Classification of viruses is based on type of nucleic acid, strategy for replication, and morphology. Virus family names end in -viridae; genus names end in -virus. A viral species is a group of viruses sharing the same genetic information and ecological niche.

toxin produced by an ascomycete plant pathogen,

Claviceps purpurea that grows on grains. The toxin is contained in sclerotia, highly resistant portions of the mycelia of the fungus that can detach. The toxin itself, ergot

Extracellular Enzymes

Coagulase Kinases Hyaluronidase Collagenase IgA proteases

Coagulase

Coagulase: coagulates fibrinogen

Coagulases

Coagulases are bacterial enzymes that coagulate (clot) the fibrinogen in blood. Fibrinogen, a plasma protein produced by the liver, is converted by coagulases into fibrin, the threads that form a blood clot.Coagulases are produced by some members of the genus Staphylococcus; they may be involved in the walling-off process in boils produced by staphylococci. However, some staphylococci that do not produce coagulases are still virulent.

Collagenase

Collagenase: hydrolyzes collagen

pneumonia many causes

Common cause of pneumonia in immunocompromised patients Pneumocystis jirovecii Most common cause of atypical/walking pneumonia Mycoplasma pneumoniae Common causative agent for pneumonia in alcoholics Klebsiella pneumoniae Can cause interstitial pneumonia in bird handlers Chlamydia psittaci (sit-ah-see) Often the cause of pneumonia in a patient who has recently visited South California, New Mexico, or West Texas Coccidioides immitis Pneumonia associated with "currant jelly" sputum Klebsiella pneumoniae Q-Fever Coxiella burnetii Associated with pneumonia acquired from airconditioners Legionella pneumophilia Most common cause of pneumonia in children 1-year-old or younger Respiratory Syncytial Virus (RSV) Most common cause of pneumonia in the neonate (birth to 28 days) Group B Streptococcus E. coli Most common cause of pneumonia in children and young adults (including college students, military recruits, and prison inmates) Mycoplasma pneumoniae Common cause of pneumonia in patients with other health problems Klebsiella pneumoniae Most common cause of viral pneumonia Respiratory Syncytial Virus (RSV) Causes a wool-sorter's disease (a life-threatening pneumonia) Bacillus anthracis Endogenous flora in 20% of adults that causes pneumonia Streptococcus pneumoniae Common bacterial cause of COPD exacerbation Haemophilus influenzae Common pneumonia in ventilator patients and those with Cystic Fibrosis Pseudomonas aeruginosa Pontiac Fever Legionella pneumophilia Pneumonia caused by Gram (+) cocci in clusters Staphylococcus aureus Pneumonia caused by Gram (+) cocci in pairs Streptococcus pneumoniae Pneumonia caused by Gram (-) rods in an 80-year-old E. coli Pneumonia caused by Gram (+) cocci in neonate Group B Streptococcus Pneumonia caused by Gram (-) rods in neonate E. coli

Where are prions most commonly found?

Contaminated meat.

Growing Animal Viruses in the Laboratory

Cultivation of some animal viruses requires whole animals. Simian AIDS and feline AIDS provide models for studying human AIDS. Some animal viruses can be cultivated in embryonated eggs. Cell cultures are animal or plant cells growing in culture media. Primary cell lines and embryonic diploid cell lines grow for a short time in vitro. Continuous cell lines can be maintained in vitro indefinitely. Viral growth can cause cytopathic effects in the cell culture.

cytokines

Cytokines are small protein molecules produced by various body cells, especially T cells, that regulate immune responses and mediate cell-to-cell communication . The excessively high levels of cytokines released by T cells enter the bloodstream and give rise to a number of symptoms, including fever, nausea, vomiting, diarrhea, and sometimes shock and even death

Three types of exotoxins

Cytotoxins Neurotoxins and Enterotoxins

Cytotoxins

Cytotoxins kill host cells or affect their function (diphtheria toxin) generaric

Place the following in the order in which they are found in a host cell: (1) capsid proteins; (2) infective phage particles; (3) phage nucleic acid. A)1, 2, 3 B)3, 2, 1 C)2, 1, 3 D)3, 1, 2 E)1, 3, 2

D

Which of the following does not initiate DNA synthesis? A.a double-stranded DNA virus (Poxviridae) B.a DNA virus with reverse transcriptase (Hepadnaviridae) C.an RNA virus with reverse transcriptase (Retroviridae) D.a single-stranded RNA virus (Togaviridae) E.none of the above

D

Which of the following is required for repairing the phosphodiester backbone of DNA during molecular cloning? a)cDNA b.)reverse transcriptase c)restriction enzymes d)DNA ligase

D

The nucleocapsid is composed of DNA and RNA and protein. DNA or RNA and protein. protein located in the nucleus. nucleic acid in the ribosome. .

DNA or RNA and protein

DNA probes

DNA probes can be used to confirm the presence of a suspected pathogen in patient samples. This diagram illustrates how a DNA probe can be used to search for a gene of interest associated with the suspected pathogen.

PINOCYTOSIS

DRINKING

HIV/AIDS(persistent)

Decreased CD4+ T cells HIV-1 and -2 (Lentivirus)

Define Spongiform Encephalopathy

Degenerative diseases of the brain characterized by the development of porous sponge-like lesions in brain tissue, and by deterioration in neurological functioning; specifically, prion disease.

Virulency

Degree of Pathogenicity

What do the attachment of animal viruses depend on?

Dependent on CHEMICAL ATTRACTION and GLYCOPROTEIN SPIKES (receptors)

General Characteristics of Viruses

Depending on one's viewpoint, viruses may be regarded as exceptionally complex aggregations of nonliving chemicals or as exceptionally simple living microbes. Viruses contain a single type of nucleic acid (DNA or RNA) and a protein coat, sometimes enclosed by an envelope composed of lipids, proteins, and carbohydrates. Viruses are obligatory intracellular parasites. They multiply by using the host cell's synthesizing machinery to cause the synthesis of specialized elements that can transfer the viral nucleic acid to other cells.

Define Primary cell lines

Derived from tissue slices; these tend to die out after only a few generations

Define Diploid cell lines

Developed from Human embryos; maintains for approx 100 generations; widely used for viruses that require a Human host

What is the LD50 for the bacterial toxin tested in the example below? Dilution (μg/kg) No. of Animals Died No. of Animals Survived a. 6 0 6 b. 12.5 0 6 c. 25 3 3 d. 50 4 2 e. 100 6 0

Dilution (μg/kg) # Animals Died # Animals Lived c. 25 3 3

How does toxigenicity differ from direct damage?

Direct damage is the damage done to the host as pathogens by using the host cell for nutrients and excreting waste. Toxigenicity is the ability for a bacteria to produce toxin.

Malignancy or Cancer

Disease characterized by the presence of one or more malignant tumors (neoplastic cells that invade neighboring tissues and may metastasize to cause tumors in distant organs or tissues.)

Occurrence of a Disease

Disease occurrence is reported by incidence (number of people contracting the disease) and prevalence (number of cases at a particular time). Diseases are classified by frequency of occurrence: sporadic, endemic, epidemic, and pandemic.

Extracellular Enzymes Secreted by the pathogen

Dissolve structural components/chemicals in the body

Extracellular Enzymes Kinase

Dissolves clot; releases bacteria from clot, allowing subsequent invasion of damage tissue Ex. Streptokinase, Staphylokinase used in clinical application for clots

Superantigens

Distract the adaptive defenses of the host causing them to produce and non-specific, exaggerated response and fail to respond to the actual invader Intense immune response due to release of cytokines from host cells Symptoms: fever, nausea, vomiting, diarrhea, shock, and death

Cauliflower mosaic virus

Double-stranded DNA, nonenveloped Caulimoviridae transmitrd by Aphids

Wound tumor virus

Double-stranded RNA, nonenveloped Reoviridae transsmited by Leafhoppers

Multiplication of Bacteriophages

During the lytic cycle, a phage causes the lysis and death of a host cell. Some viruses can either cause lysis or have their DNA incorporated as a prophage into the DNA of the host cell. The latter situation is called lysogeny. During the attachment phase of the lytic cycle, sites on the phage's tail fibers attach to complementary receptor sites on the bacterial cell. In penetration, phage lysozyme opens a portion of the bacterial cell wall, the tail sheath contracts to force the tail core through the cell wall, and phage DNA enters the bacterial cell. The capsid remains outside. In biosynthesis, transcription of phage DNA produces mRNA coding for proteins necessary for phage multiplication. Phage DNA is replicated, and capsid proteins are produced. During the eclipse period, separate phage DNA and protein can be found. During maturation, phage DNA and capsids are assembled into complete viruses. During release, phage lysozyme breaks down the bacterial cell wall, and the new phages are released. During the lysogenic cycle, prophage genes are regulated by a repressor coded for by the prophage. The prophage is replicated each time the cell divides. Exposure to certain mutagens can lead to excision of the prophage and initiation of the lytic cycle. Because of lysogeny, lysogenic cells become immune to reinfection with the same phage and may undergo phage conversion. A lysogenic phage can transfer bacterial genes from one cell to another through transduction. Any genes can be transferred in generalized transduction, and specific genes can be transferred in specialized transduction.

period of convalescence

During the period of convalescence, the person regains strength and the body returns to its prediseased state. Recovery has occurred.

period of decline,

During the period of decline, the signs and symptoms subside. The fever decreases, and the feeling of malaise diminishes. During this phase, which may take from less than 24 hours to several days, the patient is vulnerable to secondary infections.

During the period

During the period of illness, the disease is most severe

Place the following in the most likely order for biosynthesis of a bacteriophage: (1) phage lysozyme; (2) mRNA; (3) DNA; (4) viral proteins; (5) DNA polymerase. 5, 4, 3, 2, 1 3, 5, 2, 4, 1 1, 2, 3, 4, 5 2, 5, 3, 4, 1 5, 3, 4, 2, 1

E

The ability of a virus to infect an organism is regulated by A.the host species. B.the type of cells. C.the availability of an attachment site. D.cell factors necessary for viral replication. E.all of the above

E

fimbriae

E. coli

bacteriocins,

E. coli cells produce bacteriocins, proteins that inhibit the growth of other bacteria of the same or closely related species, such as pathogenic Salmonella and Shigella.

E. coli

E. coli is generally harmless as long as it remains in the large intestine; but if it gains access to other body sites, such as the urinary bladder, lungs, spinal cord, or wounds, it may cause urinary tract infections, pulmonary infections, meningitis, or abscesses, respectively.

Give an example of a Normal-sized Bacteria

E. coli-3000 x 1000 nm

PHAGOCYTOSIS

EATING

Describe the chemical and physical structure of both an enveloped and a nonenveloped virus.

ENVELOPED: in some viruses, the capsid is covered by an envelope, which chemically, usually consists of some combination of lipids, proteins, and carbs. In most cases, the envelop contains proteins determined by the viral nucleic acid and materials derived from normal host cell componants. Structurally, the enveloped virus consists of the nucleic acid>>Capsomeres>> Envelop>>Spikes(on some enveloped viruses). NONENVELOPED are viruses whose capsids are not covered by an envelope. The capsid protect the viruses from nuclease enzymes in biological fluids and promotes the viruses attachment to susceptible host cells.

Electroporation

Electroporation is one laboratory technique used to introduce DNA into eukaryotic cells.A brief electric pulse induces the formation of transient pores in the phospholipid bilayers of cells through which the gene can be introduced.

How can the complement system cause endotoxic shock?

Endotoxin binds C3b, which activates C5-C9 to cause cell lysis. This can result in free cell wall fragments, which bind more C3b, resulting in C5-C9 damage to host cell membranes

Endotoxins

Endotoxins differ from exotoxins in several ways. Endo- means "within," in this context referring to the fact that the endotoxins are located within the bacterial cells. Endotoxins are part of the outer portion of the cell wall of gram-negative bacteria Gram-negative bacteria have an outer membrane surrounding the peptidoglycan layer of the cell wall . This outer membrane consists of lipoproteins, phospholipids, and lipopolysaccharides (LPS). The lipid portion of LPS, called lipid A, is the endotoxin. Thus, endotoxins are lipopolysaccharides, whereas exotoxins are proteins. Endotoxins are released during bacterial multiplication and when gram-negative bacteria die and their cell walls undergo lysis. this reaction releases endotoxin and may lead to an immediate worsening of the symptoms, but the condition usually improves as the endotoxin breaks down

effects of endotoxin

Endotoxins exert their effects by stimulating macrophages to release cytokines in very high concentrations. At these levels, cytokines are toxic. All endotoxins produce the same signs and symptoms, regardless of the species of microorganism, although not to the same degree. These include chills, fever, weakness, generalized aches, and, in some cases, shock and even death. Endotoxins can also induce miscarriage. blood-clotting proteins, causing the formation of small blood clots. These blood clots obstruct capillaries, and the resulting decreased blood supply induces the death of tissues. This condition is referred to as disseminated intravascular coagulation (DIC).

Enterotoxins

Enterotoxins act on the gastrointestinal tract (staphylococcal toxin, E. coli heat-labile toxin, cholera toxi

Large Intestine

Escherichia coli, Bacteroides, Fusobacterium, Lactobacillus, Enterococcus, Bifidobacterium, Enterobacter, Citrobacter, Proteus, Klebsiella, and Candida (fungus) The large intestine contains the largest numbers of resident microbiota in the body because of its available moisture and nutrients. Mucus and periodic shedding of the lining prevent many microbes from attaching to the lining of the gastrointestinal tract, and the mucosa produces several antimicrobiol chemicals. Diarrhea also flushes out some of the normal microbiota.

Compare and contrast the following aspects of endotoxins and exotoxins: bacterial source, chemistry, toxicity, and pharmacology. Give an example of each toxin.

Exotoxin Endotoxin bacterial Gram + Gram - Chemistry Proteins Lipid A Toxigen High low pharm destroy certain cell systemic-fever, aches parts or physiological weakness, shock functions Examples Botulinum toxin Salmonellosis

Types of Exotoxins

Exotoxins are divided into three principal types on the basis of their structure and function: (1) A-B toxins, (2) membrane-disrupting toxins, and (3) superantigens.

Differentiate an exotoxin from an endotoxin.

Exotoxins are produce within the bacteria, and are usually pretty potent. Endotoxins are components of the cell wall called lipopolysaccharides that break off when the cell dyes, usually not as potent as exotoxins.

Exotoxins effects

Exotoxins work by destroying particular parts of the host's cells or by inhibiting certain metabolic functions. They are highly specific in their effects on body tissues. Exotoxins are among the most lethal substances known. Only 1 milligram of the botulinum exotoxin is enough to kill 1 million guinea pigs. Fortunately, only a few bacterial species produce such potent exotoxins.

Explain how drugs that bind each of the following would affect pathogenicity: iron in the host's blood Neisseria gonorrhoeae fimbriae Streptococcus pyogenes M protein

Explain how drugs that bind iron in the host's blood would affect pathogenicity Would inhibit bacteria Explain how drugs that bind Neisseria gonorrhoeae fimbriae would affect pathogenicity Would prevent of N. gonorrhoeae

Beside adhesins, these can be classified into three categories:

Extracellular Enzymes Toxins Anti-phagocytic factors

There are _______ families of RNA containing viruses that infect vertebrates. two five seven fourteen

FOURTEEN

Capsids are made of a number of capsomeres which are covalently bonded to one another. True False

False

multiplication of a DNA virus

Following attachment, entry, and uncoating, the viral DNA is released into the nucleus of the host cell. Transcription of a portion of the viral DNA—the "early" genes—occurs next. Translation follows. The products of these genes are enzymes that are required for the multiplication of viral DNA. In most DNA viruses, early transcription is carried out with the host's transcriptase (RNA polymerase); poxviruses, however, contain their own transcriptase. Sometime after the initiation of DNA replication, transcription and translation of the remaining "late" viral genes occur. Late proteins include capsid and other structural proteins. This leads to the synthesis of capsid proteins, which occurs in the cytoplasm of the host cell. After the capsid proteins migrate into the nucleus of the host cell, maturation occurs; the viral DNA and capsid proteins assemble to form complete viruses. Complete viruses are then released from the host cell.

Portals of Entry

Four major pathways Skin Mucous membranes* Parenteral route Placenta

Where do viruses obtain their viral envelopes?

From the HOST CELL'S CYTOPLASMIC MEMBRANE when they replicate or exit the host cell.

What makes it hard to prevent or treat these Retroviruses is, their __________ __________ is constantly changing

Genetic Material

Koch

German physician who played a major role in establishing that microorganisms cause specific diseases. In 1877, he published some early papers on anthrax, a disease of cattle that can also occur in humans. Koch demonstrated that certain bacteria, today known as Bacillus anthracis, were always present in the blood of animals that had the disease and weren't present in healthy animals.showed that a specific infectious disease (anthrax) is caused by a specific microorganism (B. anthracis) He later used the same methods to show that the bacterium Mycobacterium tuberculosis is the causative agent of tuberculosis.

protozoa Gardia

Giardia intestinalis, the causative agent of giardiasis, attach to host cells by a sucking disc and digest the cells and tissue fluids.

Yersina Pestis

Gram Negative Coccobacillus - Non spore forming rod - Oxidase Negative - Facultative - Glucose Fermented * Rich polysaccharide capsule present in virulent strains Reservoir - disease of small rodents - Voles, Rats, Ground Hogs* Yersinia pestis - Epidemiology Vector - Xenopsilla cheopis flea contatcts Yersinia when it takes a blood meal from infected rodent host --> organism multiplies in proventriculus of the flea --> blocking flea's GI Tract* Starving flea regurgitates infectious material when attempting to take another blood meal* (2dary vectors) Yersinia pestis - Epidemics 1) The Black Death 2) Sylvatic Plaque usually get it through fleas* Yersinia pestis - Pathology Primary exposure = flea bite Organism reaches LN ! Infected LN - swells + painful ! - " A Bubo" Pulmonary infection - transmitted by respiratory droplets*

of all the hospital patients with infections, one-third do not enter the hospital with an infection. How do they acquire these infections? What is the method of transmission of these infections?What is the reservoir of infection?

HAI- hospital acquired infections. patients may be in a weakened condition and therefore predisposed to infection. Pathogenic microorganisms are generally transmitted to patients by contact and airborne transmission. The reservoir of infection is the hospital staff, staff and other patients.

Chain of Transmission

HAIs are transmitted by direct contact between staff members and patients and between patients. Fomites such as catheters, syringes, and respiratory devices can transmit HAIs.

Which type of virus causes CERVICAL cancer?

HPV

Healthcare-Associated Infections (HAIs)

Healthcare-associated infections (HAIs) include those acquired in settings such as hospitals, nursing homes, surgical centers, and health care clinics. About 5-15% of patients acquire HAIs in the treatment environment.

Gene Guns

Heavy-metal particles coated with recombinant DNA are shot into plant protoplasts using a gene gun. The resulting transformed cells are allowed to recover and can be used to generate recombinant plants. gene gun is used to shoot gold or tungsten particles coated with recombinant DNA molecules into the plant protoplasts at high speeds. Recipient protoplast cells can then recover and be used to generate new transgenic plants

General Morphology

Helical viruses (for example, Ebola virus) resemble long rods, and their capsids are hollow cylinders surrounding the nucleic acid. Polyhedral viruses (for example, adenovirus) are many-sided. Usually the capsid is an icosahedron. Enveloped viruses are covered by an envelope and are roughly spherical but highly pleomorphic. There are also enveloped helical viruses (for example, influenza virus) and enveloped polyhedral viruses (for example, Simplexvirus). Complex viruses have complex structures. For example, many bacteriophages have a polyhedral capsid with a helical tail attached.

Hepadnaviridae

Hepadnaviridae are so named because they cause hepatitis and contain DNA . The only genus in this family causes hepatitis B. (Hepatitis A, C, D, E, F, and G viruses, although not related to each other, are RNA viruses. Hepatitis is discussed in Chapter 25.) Hepadnaviruses differ from other DNA viruses because they synthesize DNA by copying RNA, using viral reverse transcriptase. This DNA is the template for viral mRNA and the virus's DNA genome. This enzyme is discussed later with the retroviruses, the only other family with reverse transcriptase.

Identify the viral family that infects skin, mucosa, and nerve cells; causes infections that can recur because of latency, and has polyhedral geometry.

Herpesviridae

What happens 10 minutes after virus infects a cell?

Host cell becomes a Viral Reproducing Machine

What factors do viruses depend on for viral replication?

Host cell's organelles and enzymes

Host Range

Host range refers to the spectrum of host cells in which a virus can multiply. Most viruses infect only specific types of cells in one host species. Host range is determined by the specific attachment site on the host cell's surface and the availability of host cellular factors.

In the Lytic cycle, define Gene Expression

Host's Nucleic acid is destroyed, and Viral DNA is replicated using the Host cell's reproductive machinery

Hyaluronidase

Hyaluronidase: hydrolyzes hyaluronic acid

Botulinum

ID50 is 0.03ng/kg most potent

The virulence of a microbe is often expressed as the

ID50,(infectious dose for 50% of a sample population). The 50 is not an absolute value; rather, it is used to compare relative virulence under experimental conditions.

How a protein can be infectious.

If an abnormal prion protein (PrPSc) enters a cell, it changes a normal prion protein to PrPSc, which now can change another normal PrPC, resulting in an accumulation of the abnormal PrPSc.

IgA proteases

IgA proteases: destroy IgA antibodies

Food poisoning can be divided into two categories: food infection and food intoxication

In food infection, microorganism itself causes the illness. In food intoxication, the toxic the microorganism produces causes the illness.

Growing Animal Viruses in the Laboratory

In the laboratory, three methods are commonly used for culturing animal viruses. These methods involve using living animals, embryonated eggs, or cell cultures. can be grown either in suspensions of bacteria in liquid media or in bacterial cultures on solid media

How can one destroy PRIONS?

Incineration OR autoclaving in 1 N NaOH.

Cervical cancer(persistent)

Increased cell growth Human papillomavirus

Liver cancer (persistent)

Increased cell growth Hepatitis B virus

Define inflammation,and list its characteristics

Inflammation is the body's response to tissue damage. The characteristic symptoms of inflammation are redness, pain, heat, and swelling

What is meningitis?

Inflammation of the subarachnoid space or spinal fluid.

Give several examples of how microbes evade the complement system

Inhibit formation of C3b; prevent MAC formation; hydrolyze C5a

What are interferons? Discuss their roles in innate immunity

Interferons are defensive proteins. Alpha interferon and beta interferon induce uninfected cells to produce antiviral proteins. Gamma interferon is produced by lymphocytes and activates neutrophils to kill bacteria

What protrusions are present on some viral envelopes and what is their function? Glycoproteins

Involved in HOST RECOGNITION

Virion

Is a complete fully developed, infectious viral particle,composed of nucleic acid and surrounded by a protein coat, outside the host cell

What is the function of the enzyme transposase?

It cuts the DNA so the transposon can leave its current position. It cuts the DNA at the new site for a transposon. It covalently links the transposon to the new DNA site ase (enzyme)

What does the virus do once it enters its host cell?

It removes the capsid and phospholipid envelope in order to release its genetic material into the host.

lactobacilli

Just before a woman gives birth, lactobacilli in her vagina multiply rapidly. The newborn's first contact with microorganisms is usually with these lactobacilli, and they become the predominant organisms in the newborn's intestine.

Which virus causes KAPOSI'S SARCOMA?

KS-associated herpes virus

Bacteria can spread from the focal infection by what three ways?

Kinase Hyaluronidase Collagenase

Kinases

Kinases: digest fibrin clots

Koch's Postulates

Koch's postulates are criteria for establishing that specific microbes cause specific diseases. Koch's postulates have the following requirements: (1) the same pathogen must be present in every case of the disease; (2) the pathogen must be isolated in pure culture; (3) the pathogen isolated from pure culture must cause the same disease in a healthy, susceptible laboratory animal; and (4) the pathogen must be reisolated from the inoculated laboratory animal.

Exceptions to Koch's Postulates

Koch's postulates are modified to establish etiologies of diseases caused by viruses and some bacteria, which cannot be grown on artificial media. Some diseases, such as tetanus, have unequivocal signs and symptoms. Some diseases, such as pneumonia and nephritis, may be caused by a variety of microbes. Some pathogens, such as S. pyogenes, cause several different diseases. Certain pathogens, such as HIV, cause disease in humans only.

The concentration of virus that infects or kills 50% of the host cells is referred to as the LD50. ID50. ID100. LD100. LD50 AND ID50.

LD50 AND ID50.

Provide an example of a latent viral infection.

Latent Infection: provirus generally not actively replicating, remains dormant in live host cell, viral DNA permanently part of host DNA Example: HSV1, HIV and chicken pox virus

Which of the following genera is the most infectious? Genus ID50 Genus ID50 Legionella 1 cell Shigella 200 cells Salmonella 105 cells Treponema 52 cells

Legionella

Mucous membranes

Line the body cavities that are open to the environment Provide a moist, warm environment that is hospitable to pathogens Respiratory tract is the most common site of entry - entry is through the nose, mouth, or eyes Pathogens able to survive the acidic pH of the stomach may use the gastrointestinal tract as a route of entry

Enzymes

Local infections can be protected in a fibrin clot caused by the bacterial enzyme coagulase. Bacteria can spread from a focal infection by means of kinases (which destroy blood clots), hyaluronidase (which destroys a mucopolysaccharide that holds cells together), and collagenase (which hydrolyzes connective tissue collagen). IgA proteases destroy IgA antibodies.

Membrane-Disrupting Toxins

Lyse host's cells by Making protein channels in the plasma membrane Leukocidins Hemolysins Streptolysins Disrupting phospholipid bilayer

How can lysogeny turn the normally harmless E. coli into a pathogen?

Lysogeny is when viral DNA attaches to the plasmid in the bacteria. This can cause the bacteria to produce toxins and exhibit other new properties. This is called lysogenic conversion

Complementary DNA or cDNA

Made from mRNA by reverse transcription can be cloned in genomic libraries

More viruses are being grown in what type of cells? And why?

Mammalian; closest to Human cells

Portals of entry review

Many microorganisms can penetrate mucous membranes of the conjunctiva and the respiratory, gastrointestinal, and genitourinary tracts. Most microorganisms cannot penetrate intact skin; they enter hair follicles and sweat ducts. Some microorganisms can gain access to tissues by inoculation through the skin and mucous membranes in bites, injections, and other wounds. This route of penetration is called the parenteral route.

Entry

Many viruses enter into eukaryotic cells by receptor-mediated endocytosis

Benign tumor

Mass of neoplastic cells that remains in one place and is not generally harmful.

How do each of the following strategies contribute to the virulence of the pathogen? What disease does each organism cause? Strategy Pathogen Changes its cell wall after entry into host Yersinia pestis Uses urea to produce ammonia Helicobacter pylori Causes host to make more receptors Rhinovirus

Mechanical: movement out; Chemical: acidic environment in female

When injected into rats, the ID50 for Salmonella typhimurium is 106 cells. If sulfonamides are injected with the salmonellae, the ID50 is 35 cells. Explain the change in ID50 value.

Mechanical: movement out; Chemical: lysozome; acids

Membrane-disrupting toxins

Membrane-disrupting toxins contribute to virulence by killing host cells, especially phagocytes, and by aiding the escape of bacteria from sacs within phagocytes (phagosomes) into the host cell's cytoplasm.

hemolysins

Membrane-disrupting toxins that destroy erythrocytes (red blood cells), also by forming protein channels, are called hemolysins. Important producers of hemolysins include staphylococci and streptococci

leukocidins

Membrane-disrupting toxins that kill phagocytic leukocytes (white blood cells) are called leukocidins. They act by forming protein channels. Leukocidins are also active against macrophages, the phagocytes present in tissues. Most leukocidins are produced by staphylococci and streptococci.

meningitis

Meningitis is an inflammation of the membranes (meninges) surrounding your brain and spinal cord. The swelling from meningitis typically triggers symptoms such as headache, fever and a stiff neck. Most cases of meningitis in the U.S. are caused by a viral infection, but bacterial and fungal infections are other causes. Some cases of meningitis improve without treatment in a few weeks. Others can be life-threatening and require emergent antibiotic treatment.

Subacute sclerosing panencephalitis (SSPE) (persistent)

Mental deterioration Measles virus

Persistent enterovirus infection

Mental deterioration associated with AIDS Echoviruses

Lyme Disease

Mode of transmission - IXODES - sp. Ticks* Clinical - Erythema Migrans, Recurrent Arthiritis

Syphillis

Mode of transmission - person-person sexual contact Clinical - Soft Chancre, tabes Dorsalis, Aortitis

Which type of virus causes BURKETT'S LYMPHOMA?

Mono-Epstein-Barr Virus

Which type of virus causes HODGKIN'S LYMPHOMA?

Mono-Epstein-Barr Virus

Direct Damage

Most damage by bacteria, however, is done by toxins. Some bacteria can penetrate host cells by excreting enzymes or by their own motility; such penetration can itself damage the host. pathogens can disrupt host cells as they pass through and can then be extruded from the host cells by a reverse phagocytosis process, enabling them to enter other host cells

Mycosis

Mycosis(plural: mycoses) is a fungal infection of animals, including humans. Mycoses are common and a variety of environmental and physiological conditions can contribute to the development of fungal diseases.

How do viroids differ from prions?

Naked RNA molecule which infects plants Proteinaceous infectious particle that lacks nucleic acids and replicates by converting similar normal proteins into new prions. (mutation caused protein to have different folding properties)

What are viruses that lack envelopes called?

Naked viruses

Adenoviridae

Named after adenoids, from which they were first isolated, adenoviruses cause acute respiratory diseases—the common cold

Herpesviridae

Nearly 100 herpesviruses are known . They are named after the spreading (herpetic) appearance of cold sores. Species of human herpesviruses (HHV) include HHV-1 and HHV-2, both in the genus Simplexvirus, which cause cold sores; HHV-3, genus Varicellovirus, which causes chickenpox; HHV-4, genus Lymphocryptovirus, which causes infectious mononucleosis; HHV-5, genus Cytomegalovirus, which causes CMV inclusion disease; HHV-6, genus Roseolovirus, which causes roseola; HHV-7, Roseolovirus, which infects most infants, causing measleslike rashes; and HHV-8, Rhadinovirus, which causes Kaposi's sarcoma, primarily in AIDS patients.

The Opa gene is used to identify this endotoxin-producing bacterium that grows well in the high-CO2 conditions inside phagocytes.

Neisseria gonorrhoeae

Neisseria gonorrhoeae

Neisseria gonorrhoeae grows inside human epithelial cells and leukocytes. These bacteria use fimbriae and an outer membrane protein called Opa

Neisseria gonorrhoeae

Neisseria gonorrhoeae, the causative agent of gonorrhea, also has fimbriae containing adhesins, which in this case permit attachment to cells with appropriate receptors in the genitourinary tract, eyes, and pharynx

Botulism, Clostridium botulinum

Neurotoxin prevents transmission of nerve impulses; flaccid paralysis results.

Neurotoxins

Neurotoxins act on the nervous system (botulinum & tetanus toxins)

Emerging Infectious Diseases

New diseases and diseases with increasing incidences are called emerging infectious diseases (EIDs). EIDs can result from the use of antibiotics and pesticides, climatic changes, travel, the lack of vaccinations, and improved case reporting. The CDC, NIH, and WHO are responsible for surveillance and responses to emerging infectious diseases.

communicable disease and noncommunicable disease

Noncommunicable Disease A disease that cannot be spread from person to person. Communicable Disease A disease that can be spread to a person from another person, an animal, or an object.

What happens 1 minute after virus infects a cell?

Normal Host cell reproduction stops

How do normal microbiota differ from transient microbiota?

Normal microbiota is always present on or in the body. Transient microbiota is not always present and most of the time is pathogenic.

What are viruses composed of?

Nucleic acid (DNA or RNA), Protein coat (capsid), sometimes a Lipid envelope

E. coli

O157:H7

How would you describe a virus?

Obligate intracellular parasite

Vertical gene transfer

Occurs when are passed from organisms to its offspring(plants and animals)

What is one dangerous gene that can be synthesized into viral DNA during replication and then spread to human cells?

Oncogenes, a cancerous gene that can be transferred to other cells. It allows the cell to gain immortality, ultimately resulting in a tumor.

DNA Oncogenic Viruses

Oncogenic viruses are found among the Adenoviridae, Herpesviridae, Poxviridae, Papovaviridae, and Hepadnaviridae.

DNA Oncogenic Viruses

Oncogenic viruses are found within several families of DNA-containing viruses. These groups include the Adenoviridae, Herpesviridae, Poxviridae, Papovaviridae, and Hepadnaviridae. Among the papovaviruses, papillomaviruses cause uterine (cervical) cancer.EB virus,another DNA virus that causes cancer is hepatitis B virus (HBV)

Viruses to Treat Cancer

Oncolytic viruses infect and lyse cancer cells.

When counting PFUs, each clear area represents __________ __________.

One Plaque

How are endotoxins on medical equipment tested for?

One test is using the limulus amoebocyte lysate (LAL) assay, which will detect even minute amounts of endotoxin.

Matrix Proteins

Other viral proteins that fill the region between the capsid and envelope

Papovaviridae

Papovaviruses are named for papillomas (warts), polyomas (tumors), and vacuolation (cytoplasmic vacuoles produced by some of these viruses). Warts are caused by members of the genus Papillomavirus. Some Papillomavirus species are capable of transforming cells and causing cancer. Viral DNA is replicated in the host cell's nucleus along with host cell chromosomes. Host cells may proliferate, resulting in a tumor.

Portals of Exit

Pathogens leave a host by portals of exit. Three common portals of exit are the respiratory tract via coughing or sneezing, the gastrointestinal tract via saliva or feces, and the genitourinary tract via secretions from the vagina or penis. Arthropods and syringes provide a portal of exit for microbes in blood.

Compromised Host

Patients with burns, surgical wounds, and suppressed immune systems are the most susceptible to HAIs.

Persistent Viral Infections

Persistent viral infections are disease processes that occur over a long period and are generally fatal. Persistent viral infections are caused by conventional viruses; viruses accumulate over a long period.

What is the composition of the viral envelope?

Phospholipid bilayer + proteins

single-stranded RNA viruses

Picornaviruses, such as enteroviruses and polio- virus

plant viruses

Plant viruses resemble animal viruses in many respects: plant viruses are morphologically similar to animal viruses, and they have similar types of nucleic acid. In fact, some plant viruses can multiply inside insect cells. Viruses can cause color change, deformed growth, wilting, and stunted growth in their plant hosts. Some hosts, however, remain symptomless and only serve as reservoirs of infection.

Where are Viroids found? And what do they ruin?

Plants only, so far; Citrus, cucumbers, potatoes

PFUs are __________ __________ __________

Plaque forming units

What is a dissimilation plasmid?

Plasmid that codes for enzymes that trigger catabolism of certain unusual sugars and hydrocarbons.

Plasmids are

Plasmids are small, circular DNA molecules that are not connected to the main bacterial chromosome and are capable of independent replication. One group of plasmids, called R (resistance) factors, is responsible for the resistance of some microorganisms to antibiotics. In addition, a plasmid may carry the information that determines a microbe's pathogenicity. Examples of virulence factors that are encoded by plasmid genes are tetanus neurotoxin, heat-labile enterotoxin, and staphylococcal enterotoxin D. Other examples are dextransucrase, an enzyme produced by Streptococcus mutans that is involved in tooth decay; adhesins and coagulase produced by Staphylococcus aureus; and a type of fimbria specific to enteropathogenic strains of E. coli.

Plasmids, Lysogeny, and Pathogenicity

Plasmids may carry genes for antibiotic resistance, toxins, capsules, and fimbriae. Lysogenic conversion can result in bacteria with virulence factors, such as toxins or capsules.

malaria

Plasmodium, the causative agent of malaria, invade host cells and reproduce within them, causing their rupture. Toxoplasma attaches to macrophages and gains entry by phagocytosis. The parasite prevents normal acidification and digestion; thus, it can grow in the phagocytic vacuole.

The Production of Toxins

Poisonous substances produced by microorganisms are called toxins; toxemia refers to the presence of toxins in the blood. The ability to produce toxins is called toxigenicity. Exotoxins are produced by bacteria and released into the surrounding medium. Exotoxins, not the bacteria, produce the disease symptoms. Antibodies produced against exotoxins are called antitoxins. A-B toxins consist of an active component that inhibits a cellular process and a binding component that attaches the two portions to the target cell, e.g., diphtheria toxin. Membrane-disrupting toxins cause cell lysis, e.g., hemolysins. Superantigens cause release of cytokines, which cause fever, nausea, and other symptoms; e.g., toxic shock syndrome toxin. Genotoxins alter the host's DNA. Endotoxins are lipopolysaccharides (LPS), the lipid A component of the cell wall of gram-negative bacteria. Bacterial cell death, antibiotics, and antibodies may cause the release of endotoxins. Endotoxins cause fever (by inducing the release of interleukin-1) and shock (because of a TNF-induced decrease in blood pressure). The Limulus amebocyte lysate (LAL) assay is used to detect endotoxins in drugs and on medical devices.

Give an example of a small virus

Polio virus -20 nm

pollen

Pollen is a fine to coarse powdery substance comprising pollen grains which are male microgametophytes of seed plants, which produce male gametes (sperm cells).

Define Retrograde Evolution

Possibly Atypical Prokaryotes who lost their biochemical capabilities, kept only their genetic info, and regressed back to viral stage

potato yellow dwarf virus

Potato yellow dwarf virus is a plant virus of order Mononegavirales, family Rhabdoviridae and genus Nucleorhabdovirus.The virus is known for its various effects on potato plants including stunted growth, dwarfing and apical yellowing. The virus also affects the tuber as it causes cracking and malformation.

Why are continuous cell lines of more practical use than primary cell lines for culturing viruses?

Primary cell culture: Cells isolated from live tissue, tend to die off after a couple of generations. Continuous cell culture: Cells that have been transformed to never die (cancerous) that can live through infinite generations. Continuous cell lines are easier to work with and culter b/c they are immortalized.

List the 3 types of Tissue cultures

Primary cell lines, Diploid cell lines, Continuous/Immortal cell lines

Discuss how a protein can be infectious

Prion= infectious protein. Mammals make "normal" proteins called cellular PrP with alpha helix folding. Disease causing proteins called prion PrP is beta pleat folded. If an abnormal prion protein PrP^Sc enters a cell, it changes a normal prion protein to PrP^Sc, which now changes another normal prion, resulting in an accumulation of the abnormal PrP^Sc. Ex: Mad cow disease.

Prions

Prions are infectious proteins first discovered in the 1980s. Prion diseases, such as CJD and mad cow disease, all involve the degeneration of brain tissue. Prion diseases are the result of an altered protein; the cause can be a mutation in the normal gene for PrPC or contact with an altered protein (PrPSc).

Differentiate virus, and prion.

Prions are smaller than the smallest virus, they cause no immune response in a host, • Viruses and prions are pathogens that cause infections. • There are many similarities in viruses and prions • While viruses are made up of proteins and nucleic acids, prions lack in genetic code (nucleic acids) • Viruses cause lots of diseases while prions have been know to cause brain diseases only.

specialized transduction

Process of transferring cell DNA adjacent to a prophage to another cell

Skin

Propionibacterium, Staphylococcus, Corynebacterium, Micrococcus, Acinetobacter, Brevibacterium; Candida (fungus), and Malassezia (fungus) Most of the microbes in direct contact with skin don't become residents because secretions from sweat and oil glands have antimicrobial properties. Keratin is a resistant barrier, and the low pH of the skin inhibits many microbes. The skin also has a relatively low moisture content.

What does Capsid refer to?

Protein coat

What part of the E. coli T4 phage attaches to the host cell receptors? Capsid fragments around the nucleic acid. Protein fibers at the end of the phage tail. Pili of the envelope. Spikes of the envelope.

Protein fibers at the end of the phage tail.

Cell Wall Components

Proteins in the cell wall can facilitate adherence or prevent a pathogen from being phagocytized.

Spikes or attachment proteins (glycoproteins)

Proteins on the outside of envelope that play a role in the recognition and attachment of a host cell.

Which type of virus, once incorporated into the host's DNA, becomes permanent?

Provirus

Ignaz Semmelweis

Puerperal sepsis (childbirth fever) is a nosocomial infection that begins in the uterus as a result of childbirth or abortion. It is frequently caused by Streptococcus pyogenes. The infection progresses to the abdominal cavity (peritonitis) and in many cases to septicemia (proliferation of microbes in the blood).

Pyelonephritis

Pyelonephritis is an inflammation of the kidney, usually due to a bacterial infection. In the majority of cases, the infection starts within the bladder and then migrates up the ureters and into the kidneys. Ureters are two tubes that transport urine from each kidney to the bladder.

The Pyrosequencing Reaction

Pyrosequencing is a method of DNA sequencing (determining the order of nucleotides in DNA) based on the "sequencing by synthesis" principle, in which the sequencing is performed by detecting the nucleotide incorporated by a DNA polymerase. Pyrosequencing relies on light detection based on a chain reaction when pyrophosphate is released

Why R factors important in the treatment of infectious diseases

R-factors make bacteria resistant to specific antibiotics. If these occur with infectious diseases it makes them nearly impossible to treat.

helical viruses

Rabies , Ebola

Progressive encephalitis(persistent)

Rapid mental deterioration Rubella virus

Protoplast fusion.

Removal of the cell wall leaves only the delicate plasma membranes, which will fuse together, allowing the exchange of DNA.

How does replicative transposition differ from cut-and-paste transposition?

Replicative transposition results in multiple copies of the transposon in the DNA; cut-and-paste transposition has only one copy.

Under normal conditions, a Host cell has ________ ________ that prevent it from going into the ________ cycle.

Repressor proteins, Lytic

Viruses are hard to grow in Labs because they require a _________ _________ _________

Reproducing Host cell

In order the cultivate a virus successfully, it must be done in _________ __________ __________ in __________ culture

Reproducing Host cells, Tissue

HIV is known as a _____________virus

Retro

Define Continuous/Immortal cell lines

Routinely grown in a Lab; utilizing cancerous cells or transformed cells; maintains for an indefinite number of generations

Common bacterial meningitis pathogens

S. pneumoniae H. influenza N. meningitidis L. monocytogenes

Explain how drugs that bind Streptococcus pyogenes M protein would affect pathogenicity

S. pyogenes would not be able to attach to host cells and would be more prone to phagocytosis

Describe the NEGATIVE SENSE VIRUS ssRNA process

SENSE VIRUS ssRNA process. This type of virus is treated as INDIRECT mRNA, so it needs to be converted to (+) sense virus via the enzyme RNA-DEPENDENT RNA TRANSCIPTASE.

There are _______ families of DNA containing viruses that infect vertebrates. two four five seven

SEVEVEN

ENDOCYTOSIS

SWALLOW

The sequencing method involving the incorporation of ddNTPs is called __________.

Sanger sequencing, dideoxy method, or chain termination method

Name one virulence factor for fungal, protozoan, helminthic, and algal disease. Fungi:

Secretion of proteases, and toxins Protozoan: Waste products, antigenic variation Helminths: Waste products, presence Algae: Toxins

Viral Identification

Serological tests are used most often to identify viruses. Viruses may be identified by RFLPs and PCR.

Shock

Shock refers to any life-threatening decrease in blood pressure. Shock caused by bacteria is called septic shock.Like fever, the shock produced by endotoxins is related to the secretion of a cytokine by macrophages.

Watermelon wilt

Single-stranded RNA, + strand, nonenveloped Bunyaviridae infected by Whiteflies

Potato yellow dwarf virus

Single-stranded RNA, − strand, enveloped Rhabdoviridae transmitted by Leafhoppers and aphids

Cold sores (latent)

Skin and mucous membrane lesions; genital lesions Herpes simplex 1 and 2

How do DNA fragments migrate?

Smaller DNA fragments migrate through the gel easier and faster than larger fragments and are further away from the wells DNA is negatively charged Electrode placed near the wells is negatively charged DNA fragments will be repelled but attracted to the positive terminal at the far end of the gel. The agarose gel has tiny pores which the DNA fragments have to squeeze through as they migrate towards the other end of the gel In a sample, the DNA fragments are of different lengths, hence different size and weight The longer (heavier) DNA fragments will move slower than the shorter ones as they experience greater obstruction DNA fragments of the same length will move at the same speed and hence forming a band at the end of the experiment Each band contains many DNA fragments of the same size, migrating at the same distance away from the well How do DNA fragments migrate?

John Snow British physician

Snow analyzed the death records attributed to cholera, gathered information about the victims, and interviewed survivors who lived in the neighborhood. Using the information he compiled, Snow made a map showing that most individuals who died of cholera drank or brought water from the Broad Street pump

Descriptive epidemiology

Snow's search for the cause of the cholera outbreak in London is an example of descriptive epidemiology.

In some viruses, capsomeres function as enzymes as well as structural supports. Of what advantage is this to the virus?

Some bacteriophages may have issues with the cell walls, so the capsomeres act ENZYMATICALLY to cut through the cell wall and make it easier for the virus to enter the host cell.

Define Co-evolution of a Virus

Some forms replicated from RNA to DNA; others retained simple levels

Genotoxins

Some gram-negative bacteria, including Haemophilus ducreyi and Helicobacter spp., make genotoxins, which damage DNA. This causes mutations, disrupts cell division, and may lead to cancer. The first bacterial genotoxin to be discovered is cytolethal distending toxin. This toxin damages eukaryotic DNA.

Antigenic Variation

Some microbes vary expression of antigens, thus avoiding the host's antibodies.

Capsules

Some pathogens have capsules that prevent them from being phagocytized.

plant viruses

Some plant viruses also multiply in insect (vector), cellsPlant viruses must enter plant hosts through wounds or with invasive parasites, such as insects.

What can happen to the host's DNA during the synthesis phase of viral replication and how does that affect humans?

Sometimes, fragments of the host's DNA that was engulfed by new viruses are synthesized. This DNA can be deadly/harmful to humans. This deadly genetic material would then be in every virion and spread.

Crystallization of Tobacco Mosaic Virus was accomplished by Berkley. Stanley. Iwanowsky. Twort.

Stanley

Nose and Throat (Upper Respiratory System)

Staphylococcus aureus, S. epidermidis, and aerobic diphtheroids in the nose; S. epidermidis, S. aureus, diphtheroids, Streptococcus pneumoniae, Haemophilus, and Neisseria in the throat Although some normal microbiota are potential pathogens, their ability to cause disease is reduced by microbial antagonism. Nasal secretions kill or inhibit many microbes, and mucus and ciliary action remove many microbes.

Staphylococcus aureus

Staphylococcus aureus, which can cause skin infections, binds to skin by a mechanism of adherence that resembles viral attachment

Eyes (Conjunctiva)

Staphylococcus epidermidis, S. aureus, diphtheroids, Propionibacterium, Corynebacterium, streptococci, and Micrococcus The conjunctiva, a continuation of the skin or mucous membrane, contains basically the same microbiota found on the skin. Tears and blinking also eliminate some microbes or inhibit others from colonizing.

Urinary and Reproductive Systems

Staphylococcus, Micrococcus, Enterococcus, Lactobacillus, Bacteroides, aerobic diphtheroids, Pseudomonas, Klebsiella, and Proteus in urethra; lactobacilli, Streptococcus, Clostridium, Candida albicans (fungus), and Trichomonas vaginalis (protozoan) in vagina The lower urethra in both sexes has a resident population; the vagina has its acid-tolerant population of microbes because of the nature of its secretions. Mucus and periodic shedding of the lining prevent microbes from attaching to the lining; urine flow mechanically removes microbes, and the pH of urine and urea are antimicrobial. Cilia and mucus expel microbes from the cervix of the uterus into the vagina, and the acidity of the vagina inhibits or kills microbes.

What promotes bacteria multiplying in the bladder?

Stasis Incomplete emptying Higher pH

There is great diversity of adhesins

Streptococcus mutans, a bacterium that plays a key role in tooth decay, attaches to the surface of teeth by its glycocalyx. An enzyme produced by S. mutans, called glucosyltransferase, converts glucose into a sticky polysaccharide called dextran, which forms the glycocalyx. Actinomyces bacterial cells have fimbriae that adhere to the glycocalyx of S. mutans. The combination of S. mutans, Actinomyces, and dextran makes up dental plaque and contributes to dental caries

Streptococcus pyogenes

Streptococcus pyogenes produces a heat-resistant and acid-resistant protein called M protein

Mouth

Streptococcus, Lactobacillus, Actinomyces, Bacteroides, Veillonella, Neisseria, Haemophilis, Fusobacterium, Treponema, Staphylococcus, Corynebacterium, and Candida (fungus) Abundant moisture, warmth, and the constant presence of food make the mouth an ideal environment that supports very large and diverse microbial populations on the tongue, cheeks, teeth, and gums. Biting, chewing, tongue movements, and salivary flow dislodge microbes. Saliva contains several antimicrobial substances.

Streptokinase

Streptokinase breaks down the body's precursor, plasminogen, to produce plasmin

enterobactin

Structure of enterobactin, one type of bacterial siderophore. The iron (Fe3+) is indicated in red.

Etiology

Study of cause of a disease

Superantigens

Superantigens are antigens that provoke a very intense immune response. They are bacterial proteins, stimulate the proliferation of immune cells called T cells. These cells are types of white blood cells (lymphocytes) that act against foreign organisms and tissues (transplants) and regulate the activation and proliferation of other cells of the immune system. In response to superantigens, T cells are stimulated to release enormous amounts of chemicals called cytokines

Pathogenic Properties of Fungi, Protozoa, Helminths, and Algae

Symptoms of fungal infections can be caused by capsules, toxins, and allergic responses. Symptoms of protozoan and helminthic diseases can be caused by damage to host tissue or by the metabolic waste products of the parasite. Some protozoa change their surface antigens while growing in a host, thus avoiding destruction by the host's antibodies. Some algae produce neurotoxins that cause paralysis when ingested by humans.

One of the most intensively studied virulent phages which infects E. coli is T9. T4. beta. gamma.

T4

TASS

TASS is caused by (1) chemicals on surgical instruments, resulting from improper or insufficient cleaning; (2) products introduced into the eye during surgery, such as washing solutions or medications; or (3) other substances that enter the eye during or after surgery, such as topical ointments or talc from surgical gloves.

If a virus utilizes a lytic life cycle of reproduction, it will not induce tumors. True False

TRUE

Naked and enveloped viruses both may enter the host via endocytosis. True False

TRUE

Define Plaque Assay

Test for how Virulent a virus is

Bacillus anthracis can cause infection via three different portals of entry

The ID50 through the skin (cutaneous anthrax) is 10 to 50 endospores; the ID50 for inhalation anthrax is inhalation of 10,000 to 20,000 endospores; and the ID50 for gastrointestinal anthrax is ingestion of 250,000 to 1,000,000 endospores. cutaneous anthrax is significantly easier to acquire than either the inhalation or the gastrointestinal forms

Where on the virus are the recognition sites for host cells?

The OUTERMOST layer

Shuttle Vectors

The Ti plasmid of Agrobacterium tumefaciens is a useful shuttle vector for the uptake of genes of interest into plant cells. The gene of interest is cloned into the Ti plasmid, which is then introduced into plant cells. The gene of interest then recombines into the plant cell's genome, allowing for the production of transgenic plants.

Biological transmission

The arthropod bites an infected person or animal and ingests some of the infected blood

Adherence

The attachment between pathogen and host is accomplished by means of surface molecules on the pathogen called adhesins or ligands that bind specifically to complementary surface receptors on the cells of certain host tissues . Adhesins may be located on a microbe's glycocalyx or on other microbial surface structures, such as pili, fimbriae, and flagella

bacteria that has never been cultured

The bacterium Treponema pallidum is known to cause syphilis, but virulent strains have never been cultured on artificial media. The causative agent of leprosy, Mycobacterium leprae, has also never been grown on artificial media. Moreover, many rickettsial and viral pathogens cannot be cultured on artificial media because they multiply only within cells.

antitoxins

The body produces antibodies called antitoxins that provide immunity to exotoxins. When exotoxins are inactivated by heat or by formaldehyde, iodine, or other chemicals, they no longer cause the disease but can still stimulate the body to produce antitoxins.

Which part of the body do prions usually target?

The brain and its neurons. There are usually fibril deposits in the brain and a loss of brain matter.

lysogenic cycle

The cell stays alive

glycocalyx capsule

The chemical nature of the capsule appears to prevent the phagocytic cell from adhering to the bacterium. However, the human body can produce antibodies against the capsule, and when these antibodies are present on the capsule surface, the encapsulated bacteria are easily destroyed by phagocytosis.

eyes

The conjunctiva is a delicate mucous membrane that lines the eyelids and covers the white of the eyeballs. Although it is a relatively effective barrier against infection, certain diseases such as conjunctivitis, trachoma, and ophthalmia neonatorum are acquired through the conjunctiva.

Viruses and Cancer

The earliest relationship between cancer and viruses was demonstrated in the early 1900s, when chicken leukemia and chicken sarcoma were transferred to healthy animals by cell-free filtrates.

In order for a virus to cause cancer, what would it target in the host cell?

The genes in the cell that CONTROL CELL CYCLE.

Development of Disease

The incubation period is the interval between the initial infection and the first appearance of signs and symptoms. The prodromal period is characterized by the appearance of the first mild signs and symptoms. During the period of illness, the disease is at its height, and all disease signs and symptoms are apparent. During the period of decline, the signs and symptoms subside. During the period of convalescence, the body returns to its prediseased state, and health is restored.

causes of pyelonephritis

The majority of pyelonephritis cases results from Escherichia coli (E.coli) bacterial infections. This type of bacterium is primarily found in the large intestine and is excreted in your stool. The bacteria can travel up from the urethra to the bladder and kidneys, resulting in pyelonephritis. Although bacterial infection is the leading cause of pyelonephritis, other possible causes include: urinary examinations that use a cystoscope, an instrument that looks inside the bladder surgery of the bladder, kidneys, or ureters the formation of kidney stones, which are rock-like formations consisting of minerals and other waste material

transient microbiota

The microorganisms that are present in animal for a short period without causing a disease may be present for several days, weeks, or months and then disappear

The Biosynthesis of RNA Viruses

The multiplication of RNA viruses is essentially the same as that of DNA viruses, except RNA viruses multiply in the host cell's cytoplasm

microbial antagonism.

The normal microbiota can prevent pathogens from causing an infection

Growing Bacteriophages in the Laboratory

The plaque method mixes bacteriophages with host bacteria and nutrient agar. After several viral multiplication cycles, the bacteria in the area surrounding the original virus are destroyed; the area of lysis is called a plaque. Each plaque originates with a single viral particle; the concentration of viruses is expressed as plaque-forming units.

Portals of Entry

The portals of entry for pathogens are mucous membranes, skin, and direct deposition beneath the skin or membranes (the parenteral route).

Capsid and Envelope

The protein coat surrounding the nucleic acid of a virus is called the capsid. The capsid is composed of subunits, capsomeres, which can be a single type of protein or several types. The capsid of some viruses is enclosed by an envelope consisting of lipids, proteins, and carbohydrates. Some envelopes are covered with carbohydrate-protein complexes called spikes.

key reason retroviruses can contribute to cancer

The provirus, which is the double-stranded DNA molecule synthesized from the viral RNA, becomes integrated into the host cell's DNA; new genetic material is thereby introduced into the host's genome and is the key reason retroviruses can contribute to cancer.

Why are viruses specific in the kinds of hosts that they infect?

The receptors that they have on the outside can only bind to those of certain bacteria.

Why does hemolysis of red blood cells occur when a person receives a transfusion of the wrong type of blood?

The recipient's antibodies combine with donor antigens and fix complement; the activated complement causes hemolysis

Which are the most often used portals of exits?

The respiratory and gastrointestinal tract.

Epidemiology

The science of epidemiology is the study of the transmission, incidence, and frequency of disease. Modern epidemiology began in the mid-1800s with the works of Snow, Semmelweis, and Nightingale. In descriptive epidemiology, data about infected people are collected and analyzed. In analytical epidemiology, a group of infected people is compared with an uninfected group. In experimental epidemiology, controlled experiments designed to test hypotheses are performed. Case reporting provides data on incidence and prevalence to local, state, and national health officials. The Centers for Disease Control and Prevention (CDC) is the main source of epidemiological information in the United States. The CDC publishes the Morbidity and Mortality Weekly Report to provide information on morbidity (incidence) and mortality (deaths).

Severity or Duration of a Disease

The scope of a disease can be defined as acute, chronic, subacute, or latent. Herd immunity is the presence of immunity to a disease in most of the population.

The three types of symbiosis

The three types of symbiosis are commensalism (one organism benefits, and the other is unaffected), mutualism (both organisms benefit), and parasitism (one organism benefits, and one is harmed).

RNA Oncogenic Viruses

The virus's ability to produce tumors is related to the presence of reverse transcriptase. The DNA synthesized from the viral RNA becomes incorporated as a provirus into the host cell's DNA. A provirus can remain latent, can produce viruses, or can transform the host cell.

diabetes

Therapy for diabetes; better tolerated than insulin extracted from animals produced by E. coli. is produced by two different E.coli genes that are inserted into plasmids vectors and linked to the end of Beta galactosidase

PrPC

These diseases are caused by the conversion of a normal host glycoprotein called PrPC (for cellular prion protein) into an infectious form called PrPSc (for scrapie protein). The gene for PrPC is located on chromosome 20 in humans. Recent evidence suggests that PrPC is involved in regulating cell death. (Apoptosis)

Why is a complex transposon containing an antibiotic resistance gene more likely to be copied than a simple insertion sequence when the host reproduces?

They confer a survival advantage for the host.

opportunistic pathogens

They don't cause disease in their normal habitat in a healthy person but may do so in a different environment. For example, microbes that gain access through broken skin or mucous membranes can cause opportunistic infections. Or, if the host is already weakened or compromised by infection, microbes that are usually harmless can cause disease.

What is unique about complex transposons?

They have two simple transposons with another DNA sequence between them.

M protein

This protein is found on both the cell surface and fimbriae. It mediates attachment of the bacterium to epithelial cells of the host and helps the bacterium resist phagocytosis by white blood cells. The M protein thereby increases the virulence of the microorganism. Immunity to S. pyogenes depends on the body's production of an antibody specific to M protein.

Glomerulonephritis

This type of acute nephritis produces inflammation in the glomeruli. There are millions of capillaries within each kidney. Glomeruli are the tiny clusters of capillaries that transport blood and behave as filtering units. Damaged and inflamed glomeruli may not filter the blood properly.

Describe the POSITIVE SENSE VIRUS ssRNA process.

This type of virus is treated as direct mRNA by the host cell and can just go to the ribosome for DIRECT TRANSLATION.

Describe the RETROVIRUS ssRNA process.

This type of virus will undergo REVERSE TRANSCRIPTION via the enzyme REVERSE TRANSCRIPTASE. Here, the virus' RNA will become DNA in order to integrate it into the host's DNA.

Some viral genomes, composed of single-stranded RNA, act as mRNA. What advantage might these viruses have over other kinds of viruses?

Those viruses DO NOT need to go to the nucleus because they don't need to be converted from DNA to RNA. They can just REPLICATE RIGHT AWAY at the ribosome and go into translation.

necrotizing fasciitis caused by Streptococcus pyogenes

Tissue destruction from S. pyogenes can occur as fast as 2 cm of tissue per hour—much faster than the bacteria are growing.One of the enzymes responsible for the rapid spread is streptokinase. Strains that produce streptokinase digest the fibrin clot that the body uses to isolate an infection.

bacteriophage lambda

To construct a genomic library using larger fragments of genomic DNA, an E. coli bacteriophage, such as lambda, can be used as a host

What is the purpose of oncogenes?

To promote cell division (promote life) or to prevent cell death.

Patients with X-linked chronic granulomatous disease are susceptible to infections because their neutrophils don't generate an oxidative burst. What is the relation of the oxidative burst to infection?

Toxic oxygen products can kill pathogens

Toxoids

Toxoids are toxins whose toxicity has been destroyed but still elicit an immune response. Used for diphtheria and tetanus immunizations (DTaP vaccine) triggers immunity with the production of antibodies(antitoxins)

spongiform encephalopathies

Transmissible spongiform encephalopathies (TSEs), also known as prion diseases, are a group of progressive, invariably fatal, conditions that affect the brain (encephalopathies) and nervous system of many animals, including humans. large vacuoles develop in the brain

Transmission of Disease

Transmission by direct contact involves close physical contact between the source of the disease and a susceptible host. Transmission by fomites (inanimate objects) constitutes indirect contact. Transmission via saliva or mucus in coughing or sneezing is called droplet transmission. Transmission by a medium such as water, food, or air is called vehicle transmission. Airborne transmission refers to pathogens carried on water droplets or dust for a distance greater than 1 meter. Arthropod vectors carry pathogens from one host to another by both mechanical and biological transmission.

Treponema pallidum

Treponema pallidum, the causative agent of syphilis, uses its tapered end as a hook to attach to host cells. Listeria monocytogenes, which causes meningitis, spontaneous abortions, and stillbirths, produces an adhesin for a specific receptor on host cells.

All viruses must separate the nucleic acid from the capsid before replication. True False

True

The RNA phages contain only a single positive-sense strand of RNA. True False

True

Define NEOPLASIA.

UNCONTROLLED cell division in multicellular animal. Can indicate TUMOR.

colitis

Ulcerative colitis (UL-sur-uh-tiv koe-LIE-tis) is an inflammatory bowel disease (IBD) that causes long-lasting inflammation and ulcers (sores) in your digestive tract. Ulcerative colitis affects the innermost lining of your large intestine (colon) and rectum. Symptoms usually develop over time, rather than suddenly. Ulcerative colitis can be debilitating and can sometimes lead to life-threatening complications. While it has no known cure, treatment can greatly reduce signs and symptoms of the disease and even bring about long-term remission.

Animal viruses are divided into a number of families whose names end in -virus. -viridae. -viscous. -eieio.

VIRIDAE

How do viruses bind to their hosts?

Via RECEPTORS

Vibrio cholerae produces toxin and is capable of causing cholera only when it is lysogenic. What does this mean?

Vibrio cholerae becomes toxic when the new gene of virus is being replicated with the host cell's DNA so that it blends in and will not be attacked

Viral Size

Viral size is ascertained by electron microscopy. Viruses range from 20 to 1000 nm in length.

Tobamovirus

Virgaviridae transmitted by Wounds

papillomaviruses

Virtually all cervical and anal cancers are caused by human papillomavirus (HPV). A vaccine against four HPVs is recommended for 11- to 12-year-old girls and boys.

Numbers of Invading Microbes

Virulence can be expressed as LD50 (lethal dose for 50% of the inoculated hosts) or ID50 (infectious dose for 50% of the inoculated hosts).

In the Lytic cycle, define the Attachment/Absorption step.

Virus attach to a specific Host cell receptor site that allows only certain viruses to attach

In the Lytic cycle, define Assembly/Maturation

Virus makes Host cell produce more viruses, also placing capsids around the new little viruses

In the Lytic cycle, define the Penetration step.

Virus produces Lysozyme that breaks down cell wall, or membrane of Host cell, to allow the injection of the Virus's Nucleic acid into the Host cell

Bacteriophage (phage)

Virus that infects and usually destroys bacterial cells.

Pathogenic Properties of Viruses

Viruses avoid the host's immune response by growing inside cells. Viruses gain access to host cells because they have attachment sites for receptors on the host cell. Visible signs of viral infections are called cytopathic effects (CPE). Some viruses cause cytocidal effects (cell death), and others cause noncytocidal effects (damage but not death). Cytopathic effects include stopping mitosis, lysis, formation of inclusion bodies, cell fusion, antigenic changes, chromosomal changes, and transformation.

How can viruses and protozoa avoid being killed by the host's immune response?

Viruses can grow inside host cells, and some can remain latent in a host cell for prolonged periods

Recall from Chapter 1 that Koch's postulates are used to determine the etiology of a disease. Why is it difficult to determine the etiology of A.a viral infection, such as influenza? B.cancer?

Viruses cannot be easily observed in host tissue and culture in labs in order to be inoculated into a new host. Aditionally viruses are specific for their host and cells making it very difficult to substitute a laboratory animal for the third step of Koch's' postulates Some viruses can infect cells without inducing cancer.Cancer may not developed until long after infection.Cancers do not seem to be contagious.

Nucleic Acid

Viruses contain either DNA or RNA, never both, and the nucleic acid may be single- or double-stranded, linear or circular, or divided into several separate molecules. The proportion of nucleic acid in relation to protein in viruses ranges from about 1% to about 50%.

Why are viruses argued to not be living?

Viruses do not possess all the processes of life. They do not have the intracellular structures for metabolism. They do not respond to the environment. And, they cannot reproduce or grow on their own.

Viral Multiplication

Viruses don't contain enzymes for energy production or protein synthesis. For a virus to multiply, it must invade a host cell and direct the host's metabolic machinery to produce viral enzymes and components.

Isolation, Cultivation, and Identification of Viruses

Viruses must be grown in living cells. The easiest viruses to grow are bacteriophages.

Define BACTERIOPHAGE.

Viruses that affect BACTERIA.

Oncogenic virus

Viruses that are capable of producing tumors (Cancer). Cancer causing alterations to cellular DNA affects parts of the genome called oncogens.

Define GENERALISTS.

Viruses that infect MANY kind of cells in MANY different hosts.

Which type of symbiosis is best represented by the relationship between humans and E. coli?

Vitamin K production Biotin

Leukocidins

WBC Making protein channels in the plasma membrane

The Transformation of Normal Cells into Tumor Cells

When activated, oncogenes transform normal cells into cancerous cells. Viruses capable of producing tumors are called oncogenic viruses. Several DNA viruses and retroviruses are oncogenic. The genetic material of oncogenic viruses becomes integrated into the host cell's DNA. Transformed cells lose contact inhibition, contain virus-specific antigens (TSTA and T antigen), exhibit chromosome abnormalities, and can produce tumors when injected into susceptible animals.

herd immunity

When many immune people are present in a community, herd immunity exists.

How does the influenza cross the species barrier?

When the influenza crosses species it creates a new subtype by creating certain proteins on the surface of the virus

Plant viruses are carried by__________, __________ etc.

Wind, insects

the emergence of a new infectious disease is probably due to all of the following except: a) the need of bacteria to cause disease b) the ability of humans to travel by air c) changing environments (flood, drought, pollution) d) a pathogen crossing the species barrier e) the increasing human population

a

which of the following statements is not true? a) E. coli never causes disease b) E. coli provides vitamin K for its host c) E. coli often exists in a mutualistic relationship with humans d) E.coli gets nutrients from intestinal contents

a

C. difficile

a bacterium that can cause symptoms ranging from diarrhea to life-threatening inflammation of the colon. Illness from C. difficile most commonly affects older adults in hospitals or in long-term care facilities and typically occurs after use of antibiotic medications. However, studies show increasing rates of C. difficile infection among people traditionally not considered high risk, such as younger and healthy individuals without a history of antibiotic use or exposure to health care facilities.

protoplast

a gram (+) or plant cell is use to remove the cell wall

Hepatitis A virus

a nonenveloped + stranded RNA virus, is transmitted via the fecal-oral route.

fomite

a nonliving object that can spread infection Examples of fomites are tissues, handkerchiefs, towels, bedding, diapers, drinking cups, eating utensils, toys, money, and thermometers Contaminated syringes serve as fomites in transmitting AIDS and hepatitis B. Other fomites may transmit diseases such as tetanus.

The site at which a virus has infected and subsequently lysed the infected cell, releasing its progeny to infect and lyse surrounding cells, thereby forming a "clear zone", is referred to as a burst area. a lyse area. a plaque. a dead zone.

a plaque.

What is a conjugative plasmid?

a plasmid that can affect its own intercellular transfer by means of conjugation; this transfer is accomplished by a bacterium's being rendered a donor, usually with specialized pili. Synonym(s): infectious plasmid, transmissible plasmid

caspid

a protective protein coat that protects viral nucleic acid

Symbiosis

a relationship between two organisms in which at least one organism is dependent on the other

virus

a submicroscopic parasitic, filterable,agent consisting of a nucleic acid surrounded by a protein coat

Insertion sequences are composed of _____________.

a transposase gene flanked by inverted repeats.

hyaluronic acid

a type of polysaccharide that holds together certain cells of the body, particularly cells in connective tissue. This digesting action is thought to be involved in the tissue blackening of infected wounds and to help the microorganism spread from its initial site of infection.

mutualism

a typeof symbiosis in which populations or organisms are benefited For example, the large intestine contains bacteria, such as E. coli, that synthesize vitamin K and some B vitamins. These vitamins are absorbed into the bloodstream and distributed for use by body cells. In exchange, the large intestine provides nutrients used by the bacteria, allowing them to survive.

bacteriophages

a virus that infect bacteria

Plant viruses can't penetrate intact plant cells because (a) ; therefore, they enter cells by (b) . Plant viruses can be cultured in (c) .

a) a rigid of cell walls b)vectors such as sap sucking insects c)plant protoplast and insect cell culture

Persistent viral infections such as (a) might be caused by (b) that are (c) .

a.

The earliest smallpox vaccines were infected tissue rubbed into the skin of a healthy person. The recipient of such a vaccine usually developed a mild case of smallpox, recovered, and was immune thereafter. What is the most likely reason this vaccine did not kill more people? a.Skin is the wrong portal of entry for smallpox. b.The vaccine consisted of a mild form of the virus. c.Smallpox is normally transmitted by skin-to-skin contact. d.Smallpox is a virus. e.The virus mutated.

a. Skin is the wrong portal of entry for smallpox

An encapsulated bacterium can be virulent because the capsule a.resists phagocytosis. b.is an endotoxin. c.destroys host tissues. d.kills host cells. e.has no effect; because many pathogens do not have capsules, capsules do not contribute to virulence.

a. resists phagocytosis.

All of the following can occur during bacterial infection. Which would prevent all of the others? vaccination against fimbriae phagocytosis inhibition of phagocytic digestion destruction of adhesins alteration of cytoskeleton

a. vaccination against fimbriae

mycolic acid

acid that makes up the cell wall of Mycobacterium tuberculosis also increases virulence by resisting digestion by phagocytes, and the bacteria can even multiply inside phagocytes

Of what chemicals are adhesins composed?

act as specific surface recognition molecules, allowing the targeting of a particular bacterium to a particular surface such as root tissue in plants, lacrimal duct tissues in mammals, or even tooth enamel. ligands (or adhesins) on the surface of the bacteria interact in a lock-and-key fashion with complementary receptors on mucosal surfaces of the host. The adhesins are usually composed of proteins in the form of fimbriae or fibrillae and the receptors of glycolipids or glycoproteins

Indicate whether each of the following conditions is typical of subacute, chronic, or acute infections.The patient experiences a rapid onset of malaise; symptoms last 5 days.

acute

next generation sequencing

allow for the rapid and inexpensive sequencing of the genomes of many organisms, accelerating the volume of new sequence data. new, large-scale approaches that increase the speed and reduce the cost of DNA sequencing.

Hyaluronidase and collagenase:

allows bacteria to invade deeper tissues

Polymerase chain reaction

allows for the rapid amplification of a specific DNA sequence. Variations of PCR can be used to detect mRNA expression (reverse transcriptase PCR) or to quantify a particular sequence in the original sample (real-time PCR).is used to make copies of a desire piece of DNA

Polyacrylamide gel electrophoresis (PAGE)

allows for the separation of proteins by size, especially if native protein charges are masked through pretreatment with SDS.

Septicemia

also called blood poisoning, is a systemic infection arising from the multiplication of pathogens in the blood. Septicemia is a common example of sepsis.

Clostridium difficile

also in the large intestine. The normal microbiota of the large intestine effectively inhibit C. difficile, possibly by making host receptors unavailable, competing for available nutrients, or producing bacteriocins. However, if the normal microbiota are eliminated (for example, by antibiotics), C. difficile can become a problem. This microbe is responsible for nearly all gastrointestinal infections that follow antibiotic therapy, from mild diarrhea to severe or even fatal colitis (inflammation of the colon)

Direct contact transmission

also known as person-to-person transmission, is the direct transmission of an agent by physical contact between its source and a susceptible host; no intermediate object is involved.The most common forms of direct contact transmission are touching, kissing, and sexual intercourse.

A disease constantly present in a population is called

an endemic disease

subacute disease

an example is subacute sclerosing panencephalitis, a rare brain disease characterized by diminished intellectual function and loss of nervous function.

Zoonoses - defined

an infectious disease of lower animals that may be transmitted to humans. Transmission - direct, animate vectors, fomites

Nightingale's work was an example of

analytical epidemiology, in which she compared disease in soldiers and civilians

Genetic exchange in segmented viruses that allows a zoonotic virus to infect humans is termed antigenic shift. hemagglutination. genetic reassortment. antigenic drift.

antigenic shift

Bacterial kinases

are bacterial enzymes that break down fibrin and thus digest clots formed by the body to isolate the infection. One of the better-known kinases is fibrinolysin (streptokinase), which is produced by such streptococci as Streptococcus pyogenes. See the Applications of Microbiology box. Another kinase, staphylokinase, is produced by Staphylococcus aureus.

Intoxications

are caused by the presence of a toxin; not by microbial growth.

microbes that enter the body by gastrointestinal tract

are destroyed by hydrochloric acid and enzymes in the stomach or by bile and enzymes in the small intestine. Those that survive can cause disease.

Lysogenized cells are immune to any further infection by any virus.

are immune to infection by the same virus AND may have new properties.

viroids

are infectious RNA short pieces of naked RNA, only 300 to 400 nucleotides long, with no protein coat. The nucleotides are often internally paired, so the molecule has a closed, folded, three-dimensional structure that presumably helps protect it from attack by cellular enzymes. The RNA doesn't code for any proteins.nfections by viroids, such as potato spindle tuber viroid, result in losses of millions of dollars from crop damage

Viroids

are infectious pieces of RNA that cause some plant diseases, such as potato spindle tuber disease.

toxoids

are injected into the body as a vaccine, they stimulate antitoxin production so that immunity is produced. Diphtheria and tetanus can be prevented by toxoid vaccination.

sticky ends

are most useful in rDNA because they can be used two different ends of DNA that were cut by the same restriction enzyme

Exotoxins

are produced inside some bacteria as part of their growth and metabolism and are secreted by the bacterium into the surrounding medium or released following lysis Exotoxins are proteins, and many are enzymes that catalyze only certain biochemical reactions. Because of the enzymatic nature of most exotoxins, even small amounts are quite harmful because they can act over and over again. Bacteria that produce exotoxins may be gram-positive or gram-negative. he genes for most (perhaps all) exotoxins are carried on bacterial plasmids or phages. Because exotoxins are soluble in body fluids, they can easily diffuse into the blood and are rapidly transported throughout the body.

Siderophores

are released into the medium, where they take the iron away from iron-transport proteins by binding the iron even more tightly. Once the iron-siderophore complex is formed, it is taken up by siderophore receptors on the bacterial surface. Then the iron is brought into the bacterium. In some cases, the iron is released from the complex to enter the bacterium; in other cases, the iron enters as part of the complex.

Plasmids

are self replicating gene containing circular DNA a circular piece of DNA that replicates independently from the cell's chromosome. Extra chromosomal DNA

transposons

are small segments of DNA that can move (be "transposed") from one region of a DNA molecule to another.Transposons are "jumping genes" that can move from one DNA site to another (intrachromosomal, plasmid to plasmid or plasmit to chromosome). They can inactivate the recipient gene into which they insert. They often contain genes which confer resistance to antibiotics.

Pneumocystis pneumonia

as a consequence of AIDS is an example of a secondary infection

The correct order for the stages of a phage infection is: penetration, transcription, attachment, replication of nucleic acid and protein, assembly, release attachment, penetration, transcription, replication of nucleic acid and protein, assembly, release attachment, replication of nucleic acid and protein, penetration, transcription, assembly, release transcription, attachment replication of nucleic acid and protein, assembly, penetration, release

attachment, penetration, transcription, replication of nucleic acid and protein, assembly, release

all members of a group of ornithologists studying barn owls the wild have had salmonellosis (salmonella gastroenteritis). One birder is experiencing her third infection. What is the most likely source of their infections? a) the ornithologist are eating the same food b) they are contaminating their hands while handling the owl and nests c) one of the workers is a salmonella carrier d) their drinking water is contaminated

b

A drug that binds to mannose on human cells would prevent a.the entrance of Vibrio enterotoxin. b.the attachment of pathogenic E. coli. c.the action of botulinum toxin. d.streptococcal pneumonia. e.the action of diphtheria toxin.

b. the attachment of pathogenic E. coli

Which does not refer to the shape of a virus? icosahedral (isometric) helical complex bacillus

bacillus

The presence of bacteria in the blood is known as

bacteremia

why bacteria make glycocalyx

bacteria make glycocalyx material that forms capsules around their cell walls; this property increases the virulence of the species. The capsule resists the host's defenses by impairing phagocytosis, the process by which certain cells of the body engulf and destroy microbes

adhesions are bacterial or viral?

bacterial

some bacteriophage can

bacteriophages (viruses that infect bacteria) can incorporate their DNA into the bacterial chromosome, becoming a prophage, and thus remain latent and do not cause lysis of the bacterium. Such a state is called lysogeny

Viruses that infect bacteria are referred to as viralcidens. bacteriocidins. bacterialogens. bacteriophages.

bacteroiphages

Viruses may not be cultivated in live organisms. embryonated chicken eggs. tissue culture. blood agar.

blood agar.

The LD50 of botulinum toxin is 0.03 ng/kg; the LD50 of Salmonella toxin is 12 mg/kg. Which is the more potent toxin?

botulinum

In addition to lysis, animal viruses may exit the host cell by extrusion. budding. fission. fusion.

budding

The enzyme that uses RNA as a template to produce a DNA copy is called: a)a restriction enzyme b)DNA ligase c)reverse transcriptase d)DNA polymerase

c

Which of the following statements is true? a.The primary goal of a pathogen is to kill its host. b.Evolution selects for the most virulent pathogens. c.A successful pathogen doesn't kill its host before it is transmitted. d.A successful pathogen never kills its host.

c. A successful pathogen doesn't kill its host before it is transmitted.

The ID50 for Campylobacter sp. is 500 cells; the ID50 for Cryptosporidium sp. is 100 cells. Which of the following statements is false? a.Both microbes are pathogens. b.Both microbes produce infections in 50% of the inoculated hosts. c.Cryptosporidium is more virulent than Campylobacter. d.Campylobacter and Cryptosporidium are equally virulent; they cause infections in the same number of test animals. e.Cryptosporidium infections are acquired more easily than Campylobacter infections.

c. Cryptosporidium is more virulent than Campylobacter.

chickenpox virus (Varicellovirus)

can also exist in a latent state Chickenpox (varicella) is a skin disease that is usually acquired in childhood. The virus gains access to the skin via the blood. From the blood, some viruses may enter nerves, where they remain latent. Later, changes in the immune (T cell) response can activate these latent viruses, causing shingles (zoster). The shingles rash appears on the skin along the nerve in which the virus was latent. Shingles occurs in 10-20% of people who have had chickenpox.

how are bateriophages cultured?

can be grown in suspensions of bacteria in liquid media or in bacterial cultures on solid media. The use of solid media makes possible the plaque method for detecting and counting viruses. A sample of bacteriophage is mixed with host bacteria and melted agar. As the virus replicates plaques are formed.

foreign DNA

can be introduced into animal cells by micropipette

foreign DNA

can be introduced into plant cells by shooting DNA coated particles

Genomic libraries

can be made by cutting up entire genome by restriction enzymes and inserting the fragments into bacterial f plasmids or phages

echoviruses (pathogen carried by healthy individuals)

can cause intestinal diseases, and adenoviruses, which can cause respiratory diseases. Neisseria meningitidis, which often resides benignly in the respiratory tract, can cause meningitis, a disease that inflames the coverings of the brain and spinal cord. Streptococcus pneumoniae, a normal resident of the nose and throat, can cause a type of pneumonia.

Streptococcus pyogenes

can cause sore throat, scarlet fever, skin infections (such as erysipelas), and osteomyelitis (inflammation of bone), among other diseases.

nephritis (inflammation of the kidneys)

can involve any of several different pathogens, all of which cause the same signs and symptoms.

Ability to change or block the ligand or its receptor

can prevent infection

herpesviruses

can remain in host cells throughout the life of an individual. When herpesviruses are reactivated by immunosuppression (for example, AIDS), the resulting infection may be fatal.

sarcoma

cancer of connective tissue

relationship of virus to cancer

cancers are known to be caused by viruses. leukemias and cervical cancers are an example.

Adenocarcinomas

cancers of glandular epithelial tissues

The shape of the virus is determined by its nucleic acid. capsid. envelope. tail.

capsid.

Reverse transcriptase

catalyzes the synthesis of double-stranded DNA from an RNA template contains only exons and is introduced to produce DNA or cDNA from RNA template

Parrot Fever - Psittacosis

caused by Chlamydia sp = Chlamydia psattaci - old name infected birds shed bacteria through feces + nasal discharges, which can remain infectious for several months !

Cat Scratch Disease

caused by Rochalimaea (Baronella) henselae - 9% other 10% - Afipa fells Symptoms: - Papule or pustule appears 3-10 days later at site of a cat scratch* 2-3 weeks later - regional lymphadenopathy (head, neck, axilla) - persists for 2-4 months !

Bacillus anthracis

causes anthrax has multiple portals of entry such as inhalation and ingestion

Phagocytosis of gram-negative bacteria

causes the phagocytes to secrete tumor necrosis factor (TNF), sometimes called cachectin. TNF binds to many tissues in the body and alters their metabolism in a number of ways. One effect of TNF is damage to blood capillaries; their permeability is increased, and they lose large amounts of fluid. The result is a drop in blood pressure that results in shock.

Distinguish symptoms from signs as signals of disease

changes in body function that the patient feels are called symptoms. Symptoms such as weakness or pain are not measurable by a physician. Objective changes that the physician can observe and measure are called signs

Indicate whether each of the following conditions is typical of subacute, chronic, or acute infections.The patient experiences cough and breathing difficulty for months.

chronic

Describe how coagulase might contribute to pathogenicity

coagulase causes fibrinogen in blood to clot, the clot may protect bacterium from host defenses

Extracellular Enzymes Coagulase

coagulates blood clot proteins, "hiding" the bacteria

Phage-encoded proteins are coded for by host DNA. coded for by phage DNA. proteins normally present in the uninfected cell. early proteins. coded for by phage DNA AND early proteins.

coded for by phage DNA and early proteins.

collagenase

collagenase enzyme, produced by several species of Clostridium, facilitates the spread of gas gangrene. Collagenase breaks down the protein collagen, which forms the connective tissue of muscles and other body organs and tissues.

Cooperation among Microorganisms

competition among microbes that can cause disease; cooperation among microbes can also be a factor in causing disease. For example, pathogens that cause periodontal disease and gingivitis have been found to have receptors, not for the teeth, but for the oral streptococci that colonize the teeth.

The activation of the SOS system in a bacterium infected with a prophage results in

complete lysis of the bacterial culture AND destruction of the viral repressor through host protease activity.

A virion is a(n) pathogenic virus. subviral particle. complete, extracellular virus particle. enveloped virus particle.

complete, extracellular virus particle.

plaque-forming units (PFU)

concentrations of viral suspensions measured by the number of plaques are usually expressed in terms of plaque-forming units

What is the etiology of cystitis and urethritis?

cystitis and urethritis? usually caused by E. Coli; also caused by repeated urinary catheterizations; may be caused by STDs, mainly chlamydia & gonorrhea

Viruses that infect the monolayer can cause the monolayer cells to deteriorate during multiplication

cytopathic effect

The changes that occur in virally-infected cells are characteristic for a particular virus and are referred to as the cytopathic effect. phenotypic effect. genotypic expression. cytology.

cytopathic effect.

The removal of plasmids reduces virulence in which of the following organisms? Clostridium tetani Escherichia coli Salmonella enterica Streptococcus mutans Clostridium botulinum

d. Streptococcus mutans

Which of the following does not represent the same mechanism for avoiding host defenses as the others? a.Rabies virus attaches to the receptor for the neurotransmitter acetylcholine. b.Salmonella attaches to the receptor for epidermal growth factor. c.Epstein-Barr (EB) virus binds to the host receptor for complement. d.Surface protein genes in Neisseria gonorrhoeae mutate frequently. e.none of the above

d. Surface protein genes in Neisseria gonorrhoea emutate frequently

Which of the following is not a portal of entry for pathogens? mucous membranes of the respiratory tract mucous membranes of the gastrointestinal tract skin blood parenteral route

d. blood

IgA antibodies

defense against adherence of pathogens to mucosal surfaces, the body produces a class of antibodies called IgA antibodies. There are some pathogens with the ability to produce enzymes, called IgA proteases, that can destroy these antibodies. N. gonorrhoeae has this ability, as do N. meningitidis, the causative agent of meningococcal meningitis, and other microbes that infect the central nervous system.

The PCR step during which the double-stranded template molecule becomes single-stranded is called _____________.

denaturation

White blood cells called B cells (B lymphocytes),

develop into antibody-producing cells, also protect against infection

Polymerase Chain Reaction (PCR)

developed in 1983 by Kary Mullis while at Cetus Corporation. PCR has specific applications in research, permits rapid amplification in the number of copies of specific DNA sequences for further analysis, forensic, and clinical laboratories, including: determining the sequence of nucleotides in a specific region of DNA amplifying a target region of DNA for cloning into a plasmid vector identifying the source of a DNA sample left at a crime scene analyzing samples to determine paternity comparing samples of ancient DNA with modern organisms determining the presence of difficult to culture, or unculturable, microorganisms in humans or environmental samples

chronic disease

develops more slowly. The body's reactions may be less severe, but the disease is likely to continue or recur for long periods. Infectious mononucleosis, tuberculosis, and hepatitis B fall into this category

Bacteriophages and animal viruses both may enter a host cell by endocytosis. both may enter a host cell by fusion. both involve entry of the entire nucleocapsid. differ because bacteriophages leave the capsid outside the cell, while animal virus entry involves the entry of the whole nucleocapsid.

differ because bacteriophages leave the capsid outside the cell, while animal virus entry involves the entry of the whole nucleocapsid

Viruses are commonly referred to by their _________ name. locale genus disease species disease AND species

disease AND species

The common species name of the virus is based on the presence or absence of a nuclear membrane. type of nucleic acid it contains. disease the virus causes. geographic area it is found.

disease the virus causes

enzyme streptokinase

dissolves blood clotts that enduce heart attaks

Opportunistic pathogens

do not cause disease under normal conditions but cause disease under special conditions.

spread of illness

during the period of illness, people can serve as reservoirs of disease and can easily spread infections to other people. However, you should also know that people can spread infection during incubation and convalescence as well. This is especially true of diseases such as typhoid fever and cholera, in which the convalescing person carries the pathogenic microorganism for months or even years.

what is the nucleic acid in a virus

either DNA or RNA, but not both at the same time

mad cow disease

emerged in cattle in Great Britain in 1987. mad cow disease arose from feeding scrapie-infected sheep meat to cattle,

How are capsules and cell wall components related to pathogenicity? Give specific examples.

encapsulated bacteria can resist phagocytosis and continue growing. Streptococcus pneumonia and Klebsiella pneumonia produce capsules that are related to their virulence. M protein found in the cell walls of Streptococcus pyogenes and A protein in the cell walls of Staphylococcus aureus help these bacteria resist phagocytosis.

blunt ends

end of a DNA fragment resulting from the breaking of DNA molecule in which there are no unpaired bases, hence, both strands are of the same length.

When an enveloped virus adsorbs to the host cell with its protein spikes, the virions are taken into the cell by the process of penetration. production. fusion. endocytosis.

endocytosis

lytic cycle

ends with the lysis and death of the host cell

If many people in a given area acquire a certain disease in a relatively short period, it is called an

epidemic disease

epidemiologist

epidemiologist's work is assembling and analyzing data such as age, sex, occupation, personal habits, socioeconomic status, history of immunization, presence of any other diseases, and the common history of affected individuals

RFLP analysis

epidemiologists use RFLP analysis to track and identify the source of specific microorganisms implicated in outbreaks of food poisoning or certain infectious diseases. RFLP analysis can also be used on human DNA to determine inheritance patterns of chromosomes with variant genes, including those associated with heritable diseases or to establish paternity. Forensic scientists use RFLP analysis as a form of DNA fingerprinting, which is useful for analyzing DNA obtained from crime scenes, suspects, and victims. DNA samples are collected, the numbers of copies of the sample DNA molecules are increased using PCR, and then subjected to restriction enzyme digestion and agarose gel electrophoresis to generate specific banding patterns.

The science that studies when and where diseases occur and how they are transmitted in populations is called

epidemiology

The viral envelope closely resembles the prokaryotic cell wall. capsomere. eukaryotic cell membrane. cytoplasm.

eukaryotic cell membrane

If the bacterial population is eliminated by antibiotics

excessive douching, or deodorants, the pH of the vagina reverts to nearly neutral, and C. albicans can flourish and become the dominant microorganism there. This condition can lead to a form of vaginitis (vaginal infection).

Normal microbiota and the host

exist in symbiosis (living together).

An exit method used by viruses which does not immediately destroy the host bacterium is lysis. inversion. extrusion. excising.

extrusion.

In agarose gel electrophoresis, DNA will be attracted to the negative electrode.

false

agents of a local infection enter a blood or lymphatic vessel and spread to other specific parts of the body, where they are confined to specific areas of the body. This condition is called a

focal infection Focal infections can arise from infections in areas such as the teeth, tonsils, or sinuses.

streptococcal bronchopneumonia

following influenza is an example of a secondary infection that is more serious than the primary infection.

virus sizes

from 20 to 200nm

virion

fully developed viral particle composed of nucleic acid and a protein coat

Cells infected with animal viruses lyse because the release of the virions depletes the cell of energy. the virus releases enzymes that lyse the cell. functions necessary for cell survival are not carried out and the cell dies. the virus RNA and cellular protein interact to kill the cell.

functions necessary for cell survival are not carried out and the cell dies.

Identify one virulence factor that contributes to the pathogenicity of each of the following: fungi, protozoa, helminths, and algae

fungi: Secretion of proteases, and toxins protozoan: Waste products, antigenic variation helminths: Waste products, presence algae: Toxins

transformation

genes are transferred from one bacterium to another as "naked" DNA in solution.

Synthetic DNA

genes can be made in vitro with the help of DNA synthesis machine

adhesins

glycoproteins or lipoproteins,receptors on host cells are typically sugars, such as mannose.

The receptors to which animal virus attachment proteins usually bind are proteins. carbohydrates. nucleic acid. lipids. glycoproteins.

glycoproteins.

What is Neisseria gonorrhoeae?

gram-negative coffee bean-shaped bacteria responsible for gonorrhea infection

Bacterial meningitis

group B streptococci Escherichia coli Listeria monocytogenes Neisseria meningitidis (meningococcus) Streptococcus pneumoniae Haemophilus influenzae type B enteroviruses herpes simplex virus varicella zoster virus chickenpox and shingles mumps virus, HIV, and LCMV Angiostrongylus cantonensis Gnathostoma spinigerum Schistosoma cysticercosis toxocariasis baylisascariasis paragonimiasis

Why are viruses grown in eggs and not in culture media?

growth is signaled by egg death, cell damage, and lesions

Infection

growth of microorganisms in the body is the invasion or colonization of the body by pathogenic microorganisms The presence of a particular type of microorganism in a part of the body where it is not normally found is also called an infection An infection may exist in the absence of detectable disease. For example, the body may be infected with the virus that causes AIDS but experience no symptoms of the disease.example, although large numbers of E. coli are normally present in the healthy intestine, their infection of the urinary tract usually results in disease.

Portals of Entry: Placenta

happens about 2% of the time

Complex viruses

have more than one shape. Ex. Pox viruses

Pathogenic microorganisms

have special properties that allow them to invade the human body or produce toxins.

Rabies

helical viruses

Shapes of viruses and bacteriophages

helical, plyhedral/icosahedral and complex

Describe how hemolysins, leukocidins, coagulase, kinases, hyaluronidase, siderophores, and IgA proteases might contribute to pathogenicity.

hemolysins lyse red blood cells, hemolysis might supply nutrients for bacteria leukocidins destroy neutrophils and macrophages, this decreases host's resistance to infection coagulase causes fibrinogen in blood to clot, the clot may protect bacterium from host defenses kinases break down fibrin allowing the blood clot to be destroyed that was trying to isolate the bacteria hyaluronidase hydrolyzes the hyaluronic acid that binds cells together, could allow bacteria to spread through tissues siderophores take iron from the host, allowing bacteria to get iron for growth IgA proteases destroy IgA antibodies, weakening the host's defenses to its mucosal surfaces

The best-known examples of viruses that cause latent infections are polio. herpes. measles. chickenpox. herpes AND chickenpox.

herpes AND chickenpox

lysogeny

host bacterial cell and its progeny may exhibit new properties encoded by the bacteriophage DNA. Such a change in the characteristics of a microbe due to a prophage is called lysogenic conversion. As a result of lysogenic conversion, the bacterial cell is immune to infection by the same type of phage. In addition, lysogenic cells are of medical importance because some bacterial pathogenesis is caused by the prophages they contain.

What is the result of the lytic cycle?

host cell dies when the new virions are released

enveloped polyhedral (icosahedral)

human herpes virus

HeLa

immortal cell lines

Synthetic DNA can be made by

in vitro by DNA synthesis machine

Bacterial superantigens

include the staphylococcal toxins that cause food poisoning and toxic shock syndrome.

put the following in the correct order to describe the pattern of disease; period of convalescence, prodromal period, period of decline, incubation period, period of illness

incubation period, prodromal period, period of illness, period of decline, period of convalescence

Oncolytic viruses

infect and lyse cancer cells include adenovirus, vaccinia virus, and Simplexvirus.

causes of meningitis

infection with microorganisms Most infections are due to viruses bacteria, fungi, and protozoa being the next most common causes sinusitis Endocarditis spirochetes,Treponema pallidum (the cause of syphilis) and Borrelia burgdorferi (known for causing Lyme disease) cerebral malaria (malaria infecting the brain) amoebic meningitis, meningitis due to infection with amoebae such as Naegleria fowleri, contracted from freshwater sources.[4]

Healthcare-associated infections (HAIs) nosocomial diseases

infections patients acquire while receiving treatment for other conditions at a health care facility, such as a nursing home, hospital, same-day surgery center, outpatient clinic, or in-home health care environmen

Extracellular Enzymes Help pathogen maintain infection

invade further, and avoid body defenses

A region of DNA in which the sequence of nucleotides is identical to an inverted sequence on the complementary strand is known as a(n) __________.

inverted repeat.

Microbial antagonism

involves competition among microbes. One consequence of this competition is that the normal microbiota protect the host against colonization by potentially pathogenic microbes by competing for nutrients, producing substances harmful to the invading microbes, and affecting conditions such as pH and available oxygen.

Specialized transduction involves the random transmission of any gene. involves the transfer of a few specific genes. utilizes a defective virus. only involves genes near the viral DNA integration site. involves the transfer of a few specific genes, utilizes a defective virus AND only involves genes near the viral DNA integration site.

involves the transfer of a few specific genes, utilizes a defective virus AND only involves genes near the viral DNA integration site.

communicable disease

is a disease in which an infected person transmits an infectious agent, either directly or indirectly, to another person who in turn becomes infected. Chickenpox, measles, influenza, genital herpes, typhoid fever, and tuberculosis are examples.

scrapie

is a fatal, degenerative disease that affects the nervous systems of sheep and goats. It is one of several transmissible spongiform encephalopathies (TSEs), which are related to bovine spongiform encephalopathy (BSE or "mad cow disease") and chronic wasting disease of deer.

Cryptococcus neoformans

is a fungus that causes a type of meningitis; it produces a capsule that helps it resist phagocytosis. Some fungi have become resistant to antifungal drugs by decreasing their synthesis of receptors for these drugs.

Microarray technology

is a nucleic acid hybridization technique that allows for the examination of many thousands of genes at once to find differences in genes or gene expression patterns between two samples of genomic DNA or cDNA,

protoplasts

is a plant, bacterial or fungal cell that had its cell wall completely or partially removed using either mechanical or enzymatic means.In laboratories, plant viruses are cultured in protoplasts (plant cells with the cell walls removed) and in insect cell cultures.

prodromal period

is a relatively short period that follows the period of incubation in some diseases. The prodromal period is characterized by early, mild symptoms of disease, such as general aches and malaise.

Dental plaque

is actually a biofilm that mineralizes over time, creating what is commonly known as tartar. It is estimated that biofilms are involved in 65% of all human bacterial infections

primary infection

is an acute infection that causes the initial illness.

ergot

is an alkaloid that can cause hallucinations resembling those produced by LSD (lysergic acid diethylamide); in fact, ergot is a natural source of LSD. Ergot also constricts capillaries and can cause gangrene of the limbs by preventing proper blood circulation in the body. Although C. purpurea still occasionally occurs on grains, modern milling usually removes the sclerotia.

Hyaluronidase

is another enzyme secreted by certain bacteria, such as streptococci. It hydrolyzes hyaluronic acid, a type of polysaccharide that holds together certain cells of the body, particularly cells in connective tissue.Hyaluronidase is also produced by some clostridia that cause gas gangrene. For therapeutic use, hyaluronidase may be mixed with a drug to promote the spread of the drug through a body tissue.

The protein coat of a virus a.is called a capsomere. b.is called a capsid. c.protects the nucleic acid. d.is involved in recognition of host cell receptors. e.is called a capsid, protects the nucleic acid AND is involved in recognition of host cell receptors.

is called a capsid, protects the nucleic acid AND is involved in recognition of host cell receptors.

The protein coat of a virus

is called a capsomere

Mycobacterium tuberculosis

is implicated in diseases of the lungs, skin, bones, and internal organs

noncommunicable disease

is not spread from one host to another. These diseases are caused by microorganisms that normally inhabit the body and only occasionally produce disease or by microorganisms that reside outside the body and produce disease only when introduced into the body. An example is tetanus: Clostridium tetani produces disease only when it is introduced into the body via abrasions or wounds.

AIDS

is often accompanied by a common opportunistic infection, Pneumocystis pneumonia, caused by the opportunistic organism Pneumocystis jirovecii (see Figure 24.19). This secondary infection can develop in AIDS patients because their immune systems are suppressed. Before the AIDS epidemic, this type of pneumonia was rare

secondary infection

is one caused by an opportunistic pathogen after the primary infection has weakened the body's defenses

local infection

is one in which the invading microorganisms are limited to a relatively small area of the body. Some examples of local infections are boils and abscesses.

acute disease

is one that develops rapidly but lasts only a short time; a good example is influenza.

subclinical (inapparent) infection

is one that doesn't cause any noticeable illness. Poliovirus and hepatitis A virus, for example, can be carried by people who never develop the illness.

plants line of defense

is the cell wall, Viruses must enter through wounds or be assisted by other plant parasites, including nematodes, fungi, and, most often, insects that suck the plant's sap. Once one plant is infected, it can spread infection to other plants in its pollen.

incubation period

is the interval between the initial infection and the first appearance of any signs or symptoms.

The incidence

is the number of people in a population who develop a disease during a particular time period. It's an indicator of the spread of the disease.

DNA sequencing

is the process of determining the sequence of nucleotides (As, Ts, Cs, and Gs) in a piece of DNA.

plasma membrane ruffling

is the result of disruption in the cytoskeleton of the host cell The microbe sinks into the ruffle and is engulfed by the host cell.

Pathology

is the scientific study of disease (pathos = suffering; logos = science). pathology is concerned with the structural and functional changes brought about by disease and their effects on the body.

Contact transmission

is the spread of a disease agent by direct contact, indirect contact, or droplet transmission.

biotechnology

is the use of microorganisms cells or cell components to make a product

Biotechnology

is the use of microorganisms, cells, or cell components to make a product.

Reverse transcriptase PCR (RT-PCR)

is used for obtaining DNA copies of a specific mRNA molecule. RT-PCR begins with the use of the reverse transcriptase enzyme to convert mRNA molecules into cDNA.

genetic modification

is used to produce for pest resistant crops gene degrative enzyme to clean up toxic wastes,Alylases cellylases and enzymes for clothing production and for human growth factor

botulism

is usually due to ingestion of the exotoxin, not to a bacterial infection.

protoplast fusion

joining of cells that have cell walls have been removed

Phages that can either replicate and cause cell lysis or can integrate their DNA into the host DNA are called lysogenic phages. lytic phages. virulent phages. segmented phages.

lysogenic phages.

lytic cycle vs. lysgenic cycle

lytic cycle uses up all the nutrients in the host cell and cause cell lysis to obtain an envelope, while lysogenic cycle stays in the host cell with out harming the cell

diseases caused by prions (proteins)

mad cow disease human diseases are kuru, Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker syndrome, and fatal familial insomnia. can be genetic or transmitted

vaccine for hepatitis B

made by yeast carrying a gene for part of the hepatitis virus (the yeast produces a viral coat protein.

Diploid cell lines

made from human embryos and can last for 100 generations

Primary cell lines

made of tissue slices and die out after a few generations

predisposing factor

makes the body more susceptible to a disease and may alter the course of the disease.females have a higher incidence of urinary tract infections than males, whereas males have higher rates of pneumonia and meningitis.

Pathogenesis

manner in which a disease develops

protein-based tests

many pathogens, such as the bacterium Helicobacter pylori, which causes stomach ulcers, can be detected using protein-based tests. In addition, an increasing number of highly specific and accurate DNA amplification-based identification assays can now detect pathogens such as antibiotic-resistant enteric bacteria, herpes simplex virus, varicella-zoster virus, and many others.

Cells taken from a tumor may be used to grow viruses. can be cultivated in vitro indefinitely. may be used to grow bacteriophages. divide 50 times and then die. may be used to grow viruses AND can be cultivated in vitro indefinitely.

may be used to grow viruses AND can be cultivated in vitro indefinitely

Outside of living cells, viruses are scavenging glucose. slowly stockpiling ATP from the mitochondria. using cilia to move to the next host. metabolically inert.

metabolically inert.

agarose gel electrophoresis

method for separating DNA fragments of different sizes. Electric field is passed through agarose gel in an electrophoresis chamber DNA samples loaded on one end migrate to the other during the process. allows for the separation of DNA molecules based on size.

DNA is protected from restriction enzymes by being sequestered in a lysosome. turned into RNA. methylated. made into double stranded RNA.

methylated

Skin

microbes gain access to the body through openings in the skin, such as hair follicles and sweat gland ducts. Larvae of the hookworm actually bore through intact skin, and some fungi grow on the keratin in skin or infect the skin itself.

invasins

microbes produce surface proteins called invasins that rearrange nearby actin filaments of the cytoskeleton. For example, when S. typhimurium makes contact with a host cell, invasins of the microbe cause the appearance of the host cell plasma membrane to resemble the splash of a drop of a liquid hitting a solid surface.

The Parenteral Route

microorganisms gain access to the body when they are deposited directly into the tissues beneath the skin or into mucous membranes when these barriers are penetrated or injured Punctures, injections, bites, cuts, wounds, surgery, and splitting of the skin or mucous membrane due to swelling or drying can all establish parenteral routes. HIV, the hepatitis viruses, and bacteria that cause tetanus and gangrene can be transmitted parenterally.

systemic (generalized) infection

microorganisms or their products are spread throughout the body by the blood or lymph. Measles is an example of a systemic infection.

Normal microbiota

microorganisms that colonize a host without causing a disease , also called normal flora

Define symbiosis. Differentiate commensalism, mutualism, and parasitism, and give an example of each.

mutualism a symbiotic relationship where both partners benefit commensalism symbiotic relationship where one partner benefits and the other is unaffected parasitism symbiotic relationship where one partner benefits by obtaining nutrients at the expense of the other partner

One group of animal viruses that are able to agglutinate red blood cells are the coronavirus. retrovirus. reovirus. myxovirus.

myxovirus

Bacillus Anthracis

native to hoofed domestic herivorous animals - cattle, horses, etc Large, Strongly Gram + Rods Form central endospores = heat resistant Non motile ** Non hemolytics - polypeptide capusle Produces Capsule grows in chains + becomes very long !

Naming Exotoxins

neurotoxins attack nerve cells, cardiotoxins attack heart cells, hepatotoxins attack liver cells, leukotoxins attack leukocytes, enterotoxins attack the lining of the gastrointestinal tract, and cytotoxins attack a wide variety of cells diphtheria toxin (cause of diphtheria) and tetanus toxin (cause of tetanus). Other exotoxins are named for the specific bacterium that produces them, for example, botulinum toxin (Clostridium botulinum) and Vibrio enterotoxin (Vibrio cholerae).

The __________ blot technique is used to find an RNA fragment within a sample that is complementary to a DNA probe.

northern

persistent viral infection (or chronic viral infection)

occurs gradually over a long period. Typically, persistent viral infections are fatal.

Indirect contact transmission

occurs when the agent of disease is transmitted from its reservoir to a susceptible host by means of a nonliving object.

The prevalence

of a disease is the number of people in a population who develop a disease at a specified time, regardless of when it first appeared. Prevalence takes into account both old and new cases.

wound tumor virus

on corn and sugarcane ,s an invertebrate and plant virus

retroviruses contain

oncogenes; others contain promoters that turn on oncogenes or other cancer-causing factors.

Viruses capable of inducing tumors in animals are called

oncogenic viruses or oncoviruses

Staphylococcus epidermidis

one commensals; include Staphylococcus epidermidis that inhabit the surface of the skin, the corynebacteria that inhabit the surface of the eye, and certain saprophytic mycobacteria that inhabit the ear and external genitals. These bacteria live on secretions and sloughed-off cells, and they bring no apparent benefit or harm to the host.

RNA Oncogenic Viruses

only the oncoviruses in the family Retroviridae cause cancer

A-B toxins

onsist of two parts designated A and B, both of which are polypeptides. Most exotoxins are A-B toxins. The A part is the active (enzyme) component, and the B part is the binding component.

symptoms

or changes in body function, such as pain and malaise (a vague feeling of body discomfort).

epidemic disease that occurs worldwide is called a

pandemic disease

another kind of symbiosis, one organism benefits by deriving nutrients at the expense of the other

parasitism

Disease-causing microorganisms are called

pathogens

aflatoxin

peanut butter is occasionally recalled because of excessive amounts of aflatoxin, which has carcinogenic properties. Aflatoxin is produced by the growth of the mold Aspergillus flavus. When ingested, the toxin might be altered in a human body to a mutagenic compound.

Viroids cause disease in animals. plants. bacteria. fungus.

plants

Microbes in the gastrointestinal tract can cause

poliomyelitis, hepatitis A, typhoid fever, amebic dysentery, giardiasis, shigellosis (bacillary dysentery), and cholera. These pathogens are then eliminated with feces and can be transmitted to other hosts via contaminated water, food, or fingers.

IL-1 and TNF.

presence of gram-negative bacteria such as Haemophilus influenzae type b in cerebrospinal fluid causes the release of IL-1 and TNF. These, in turn, cause a weakening of the blood-brain barrier that normally protects the central nervous system from infection. The weakened barrier lets phagocytes in, but this also lets more bacteria enter from the bloodstream.

Protozoa

presence of protozoa and their waste products often produces disease symptoms in the host

Normal tissue taken from animals and prepared immediately as media for viral growth is termed a(n) advantageous group. monolayer culture. plaque. primary culture.

primary culture

DNA replication requires the use of

primers

Phage-encoded enzymes are all produced simultaneously. produced in a sequential manner. strictly host enzymes. used to customize the cell for viral production. produced in a sequential manner AND used to customize the cell for viral production.

produced in a sequential manner AND used to customize the cell for viral production.

apoptosis

programed cell death

colony-stimulating factor genes

promote white blood cells production.

A virion is composed of lipid, protein, and either RNA or DNA. protein and either RNA or DNA. protein and both, RNA and DNA. protein, either RNA or DNA, and possibly lipid.

protein, either RNA or DNA, and possibly lipid.

iron carrier proteins

proteins, , transferrin, and ferritin, as well as hemoglobin. carry low iron amounts of iron in the body. Pathogens need iron for growth

Antibodies

provide immunity by such actions as neutralizing toxins, inhibiting the attachment of a pathogen to host cells, and helping to lyse pathogens.

The approximate viral concentration of a sample may be determined by quantal assay. endpoint assay. the titer. the lysate assay.

quantal assay

During attachment of phage to E. coli, the phage actively seek out the bacteria. randomly bump into the bacteria. attach to proteins or carbohydrates on the bacterial surface. attach to the bacterial RNA. randomly bump into the bacteria AND attach to proteins or carbohydrates on the bacterial surface.

randomly bump into the bacteria AND attach to proteins or carbohydrates on the bacterial surface.

Acute Infection:

rapid onset, short duration, host cell destroyed. Ex: Polio, Influenza and Cold viruses

After adhering, Shigella and E. coli induce ?

receptor-mediated endocytosis as a vehicle to enter host cells and then multiply within them

Adhesins/ligands bind to

receptors on host cells

Florence Nightingale

recorded statistics on epidemic typhus in the English civilian and military populations.

toxemia

refers to the presence of toxins in the blood

Toxemia

refers to the presence of toxins in the blood (as occurs in tetanus), and viremia refers to the presence of viruses in blood.

viremia

refers to the presence of viruses in blood.

symbiosis

relationship between two organisms in which at least one organism is dependent on the other

sarcoma

remaining liquid after blood plasma is clotted with antibodies

How does phage DNA remain latent in the lysogenic cycle?

repressor proteins bind to operon which stops transcription

Yellow Fever

reservoir - MONKEYS* New world disease Vector - Aedes Aegypti** Symptoms of hemorrhagic fever with added hepatic failure + JAUNDICE !

Mucous Membranes

respiratory tract, gastrointestinal tract, genitourinary tract, and conjunctiva, a delicate membrane that covers the eyeballs and lines the eyelids.Most pathogens enter through the mucous membranes of the gastrointestinal and respiratory tracts.

viral vectors

retroviruses,adenoviruses,herpes viruses are used in gene therapy

The ability of retroviruses to induce tumors is related to their production of

reverse transcriptase

When Retroviruses produce __________ ____________ , they can use RNA as the template to make __________

reverse transcriptase, DNA

Helminths

roundworm Wuchereria bancrofti ,the causative agent of elephantiasis.

latent disease

s one in which the causative agent remains inactive for a time but then becomes active to produce symptoms of the disease; an example is shingles, one of the diseases caused by varicella virus.

Candida albicans and Trichophyton

secrete proteases. These enzymes may modify host cell membranes to allow attachment of the fungi.

What tests could you use to identify influenza virus in a patient?

serological methods such as western blotting.

The genitourinary tract is a portal of entry for

sexually transmitted infections (STIs) may penetrate an unbroken mucous membrane. Others require a cut or abrasion of some type. Examples of STIs are HIV infection, genital warts, chlamydia, herpes, syphilis, and gonorrhea.

adenovirus

shape of an icosahedron

Of what value are siderophores?

siderophores gather iron for the bacteria by taking away the iron from iron-transport proteins of the cell.

shotgun sequencing

small pieces of a genome of a free-living cell are sequenced, and the sequences are then assembled using a computer. Any gaps between the pieces then have to be found and sequenced .This technique can be used on environmental samples to study the genomes of microorganisms that haven't been cultured. The study of genetic material taken directly from environmental samples is called metagenomics. a genome is cut into pieces, and each piece is sequenced. Then the pieces are fit together. There may be gaps if a specific DNA fragment was not sequenced.

plasmids

small pieces of typically circular, double-stranded DNA that replicate independently of the bacterial chromosome In recombinant DNA technology, plasmids are often used as vectors, DNA molecules that carry DNA fragments from one organism to another. Plasmids used as vectors can be genetically engineered by researchers and scientific supply companies to have specialized properties

The protein projections on the surface of a virus that are involved in attachment to the host cell are called suckers. pili. cilia. spikes. hooks.

spikes

If a particular disease occurs only occasionally, it is called a

sporadic disease

Viroids characteristically are composed of ssRNA. dsRNA. ssDNA. dsDNA.

ssRNA

RNA phages usually contain dsRNA. dsDNA. ssRNA. ssDNA.

ssRNA.

streptolysins

streptolysins can cause lysis not only of red blood cells, but also of white blood cells (whose function is to kill the streptococci) and other body cells.streptolysin is called streptolysin S (SLS) because it is stable in an oxygen environment

what are strict pathogens?

strict pathogens are microbes that often cause disease in healthy individuals IF THEY GET PAST FIRST LINE BARRIER DEFENSES 1. have high level of virulence 2. multiple virulence factors

the patient has no apparent symptoms and is known as carrier

subacute

Ebola Disease

sudden febrile ilness, vascular collapse, internal bleeding, death internal bleeding to mucous membranes*

Microinjection

technique for introducing DNA into eukaryotic cells. A microinjection needle containing recombinant DNA is able to penetrate both the cell membrane and nuclear envelope.

Site directed mutagenesis

technique used to modify a gene in a specific location to produce a desired polypeptide

biofilms colonize

teeth, medical catheters, stents, heart valves, hip replacement components, and contact lenses.

similarities between the base sequences of viroids and introns

that introns are sequences of genetic material that don't code for polypeptides. This observation has led to the hypothesis that viroids evolved from introns, leading to speculation that researchers may eventually discover animal viroids.

heat-labile means:

that its heat sensitive; can be destroyed by heat

Compare pathogenicity with virulence.

the ability of a microorganism to produce a disease is called pathogenicity. The degree of pathogenicity is virulence

In the presence of antigens

the body produces proteins called antibodies, which bind to the antigens and inactivate or destroy them. However, some pathogens can alter their surface antigens, by a process called antigenic variation

Why are transformed cells referred to as "immortal"?

the cells can be grown indefinitely

what affect colonization of microbiota

the chewing actions of the teeth and tongue movements can dislodge microbes attached to tooth and mucosal surfaces. In the gastrointestinal tract, the flow of saliva and digestive secretions and the various muscular movements of the throat, esophagus, stomach, and intestines can remove unattached microbes. The flushing action of urine also removes unattached microbes. In the respiratory system, mucus traps microbes, which cilia then propel toward the throat for elimination.age, nutritional status, diet, health status, disability, hospitalization, stress, climate, geography, personal hygiene, living conditions, occupation, and lifestyle.

case control method

the epidemiologist looks for factors that might have preceded the disease. A group of people who have the disease is compared with another group of people who are free of the disease. For example, one group with meningitis and one without the disease might be matched by age, sex, socioeconomic status, and location.

cohort method

the epidemiologist studies two populations: one that has had contact with the agent causing a disease and another that has not (both groups are called cohort groups). For example, a comparison of one group composed of people who have received blood transfusions and one composed of people who have not could reveal an association between blood transfusions and the incidence of hepatitis B virus.

bacteriophage genes that contribute to pathogenicity are:

the genes for diphtheria toxin, erythrogenic toxins, staphylococcal enterotoxin A and pyrogenic toxin, botulinum neurotoxin, and the capsule produced by Streptococcus pneumoniae. The gene for Shiga toxin in E. coli O157 is encoded by phage genes. Pathogenic strains of Vibrio cholerae carry lysogenic phages. These phages can transmit the cholera toxin gene to nonpathogenic V. cholerae strains, increasing the number of pathogenic bacteria.

the northern blot

the northern blot, another variation of the Southern blot, RNA (not DNA) is immobilized on the membrane and probed. Northern blots are typically used to detect the amount of mRNA made through gene expression within a tissue or organism sample.

What part of the attached bacteriophage enters through the host cell wall? the entire virus only the enzymes necessary for replication the nucleic acid the nucleic acid and capsid the capsid only

the nucleic acid

Bacteriophage Lambda (λ): The Lysogenic Cycle

the phage remains latent (inactive). The participating bacterial host cells are known as lysogenic cells.

transformation

the process in which genes are transferred from one bacterium to another as naked DNA in solution.that is, they acquire properties that are distinct from the properties of uninfected cells or from infected cells that don't form tumors.

During penetration of E. coli by the T4 phage lysozyme is used to allow entry of the phage capsid. the tail acts as a "hypodermic needle", injecting the phage DNA into the cell. the protein fibers digest a hole in the cell wall. the bacterial receptor molecules open a hole through the cell wall.

the tail acts as a "hypodermic needle", injecting the phage DNA into the cell.

Sanger DNA sequencing

the target DNA is copied many times, making fragments of different lengths. Fluorescent "chain terminator" nucleotides mark the ends of the fragments and allow the sequence to be determined.

Sepsis

toxic inflammatory condition arising from the spread of microbes, especially bacteria or their toxins, from a focus of infection.

toxins

toxins kill host cells, releasing their iron and thereby making it available to the bacteria. Toxins are poisonous substances that are produced by certain microorganisms. primary factor contributing to the pathogenic properties of microbes

All of the following are processes used to introduce DNA molecules into bacterial cells except: transformation transduction transcription conjugation

transcription

generalized transduction

transfer of bacterial chromosome fragments from one cell to another by a bacteriophage

Inserting Foreign DNA into Cells

transformation, a procedure during which cells can take up DNA from the surrounding environment electroporation uses an electrical current to form microscopic pores in the membranes of cells; the DNA then enters the cells through the pores protoplast fusion shoot it directly through the thick cellulose walls using a gene gun DNA can be introduced directly into an animal cell by microinjection

Continuous cell lines

transformed cells that last an indefinite number of generations

ffects of toxins

transported by the blood or lymph can cause serious, and sometimes fatal, effects. Some toxins produce fever, cardiovascular disturbances, diarrhea, and shock. Toxins can also inhibit protein synthesis, destroy blood cells and blood vessels, and disrupt the nervous system by causing spasms.

Droplet transmission

trasnmittion of pathogen via samall droplets (mucus droplets)These droplets are discharged into the air by coughing, sneezing, laughing, or talking and travel less than 1 meter from the reservoir to the host. One sneeze may produce 20,000 droplets.Examples of diseases spread by droplet transmission are influenza, pneumonia, and pertussis (whooping cough).

T cells

type of white blood cell involved in the immune response.Leukocyte

Retroviruses are unique in that they replicate in nervous system cells. do not have a capsid. use RNA as a template to make DNA. use DNA as a template to make RNA.

use RNA as a template to make DNA

Viral Vectors

used in gene therapy to introduce healthy genes into human patients suffering from diseases that result from genetic mutations. Viral genes can be deleted and replaced with the gene to be delivered to the patient;3 the virus then infects the host cell and delivers the foreign DNA into the genome of the targeted cell. Adenoviruses are often used for this purpose because they can be grown to high titer and can infect both nondividing and dividing host cells

culturing animal viruses

using cell cultures

culturing animal viruses

using living animals

attachment proteins are bacterial or viral?

viral

the diseases that can be transmitted by direct contact

viral respiratory tract diseases (the common cold and influenza), staphylococcal infections, hepatitis A, measles, scarlet fever, and sexually transmitted infections (syphilis, gonorrhea, and genital herpes). Direct contact is also one way to spread AIDS and infectious mononucleosis.

What are the three (3) basic viral shapes? Give examples for each.

viral shapes? Give examples for each. 1. Helical (Tobacco Mosaic Virus) 2. Polyhedral (common cold) 3. Complex (small pox; rabies)

Virulence factors contributing to an organism's

virulence Adhesion factors Biofilms Extracellular enzymes Toxins Antiphagocytic factors

A phage that replicates inside the host cell and then lyses its host during its release is a virulent or lytic phage. latent phage. lysogenic phage. dormant phage.

virulent or lytic phage

Persistent Infection:

virus actively replicates in host cell; host cell remains alive, viral production for extended period via budding. Ex: Measles and Hep B viruses

Transformed cells

viruses and carcinogens transform normal cells into tumor cells that can influence cellular growth to a higher than normal rate.

how can viruses and protozoa avoid being killed by the host's immune response?

viruses avoid the hosts immune response by growing inside host cells; some can remain latent in a host cell for prolonged periods. Some protozoa avoid the immune response by mutations that change their antigens.

Nonliving Reservoirs

water and soil which house funigi and mycosis and systemic infections,Clostridium botulinum, the bacterium that causes botulism; and C. tetani, the bacterium that causes tetanus. Because both species of clostridia are part of the normal intestinal microbiota of horses and cattle, the bacteria are found especially in soil where animal feces are used as fertilizer.Water is the non living reservoir for cholera Other nonliving reservoirs include foods that are improperly prepared or stored. They may be sources of diseases such as trichinellosis and salmonellosis.

Discuss how a protein can be infectious.

when a protein becomes altered. Usually occurs in prions like the Transmissible Spongiform Encephalopathies.

how can a local infection become a systemic infection?

when microorganisms causing a local infection enter a blood or lymph vessel and are spread throughout the body, a systemic infection can result

signs

which are objective changes the physician can observe and measure. Frequently evaluated signs include lesions (changes produced in tissues by disease), swelling, fever, and paralysis.

Limulus amebocyte lysate (LAL) assay

which can detect even minute amounts of endotoxin. The hemolymph (blood) of the Atlantic coast horseshoe crab, Limulus polyphemus, contains white blood cells called amebocytes, which have large amounts of a protein (lysate) that causes clotting. In the presence of endotoxin, amebocytes in the crab hemolymph lyse and liberate their clotting protein. The resulting gel-clot (precipitate) is a positive test for the presence of endotoxin. The degree of the reaction is measured using a spectrophotometer

Simplexvirus

which produces cold sores. This virus inhabits the host's nerve cells but causes no damage until it is activated by a stimulus such as fever or sunburn—hence the term fever blister.

Plant viruses enter the host plant via wound sites. specific receptors. nonspecific receptors. seeds.

wound sites

The presence of normal microbiota inhibits the overgrowth of

yeast Candida albicans, which can grow when the balance between normal microbiota and pathogens is upset and when pH is altered