MCB 100 Exam 2 (Lecture 11 start)
Glycosidases
hydrolyze sugars/polysaccharides
What tools would the doctor use to diagnose this disease?
identification of the budding yeast in KOH-prepared samples of skin scrapings or sputum from the patient
Healthy humans typically become infected with T. gondii by_____
ingesting undercooked meat containing the disease
Listeriosis
is a severe human and animal disease caused by the Gram positive pathogen Listeria monocytogenes (most common in humans) and Listeria ivanov. This disease can cause spontaneous abortion
What is the name of the antifungal drug that Nate is taking?
ketoconazole
fruiting bodies
macroscopic reproductive structures that fungi produce
Viruses can influence manipulate the ________environment
marine
Which of the following symptoms is LEAST characteristic of Clostridium perfringens food poisoning?
moderate vomiting and fever
Motility
movement (not adhesion) involves flagellar, twitching or gliding motility.
Bacteriophage adhering to mucus provide a _____-______ _________immunity?
non-host derived
The nutritional requirement to oxidize amino acids and Kreb's cycle intermediates means Rickettsias are __________.
obligate intracellular parasites
In 90% of cases, a spotted non-itchy rash forms on the __________, particular to rickettsiosis.
palms and soles
What do Archaea lack?
peptidoglycan
Which structure is characteristic of Candida?
pseudohyphae
Listeria organism type (temperature)
psychrophile
Analysis of the second swab has confirmed that the causative organism is Streptococcus pyogenes, a gram-positive organism. Imagine that you are the technician looking at the Gram stain from Shelly's culture. What would you expect to see as you look through the microscope?
purple, spherical-shaped organisms arranged in chainlike formations
One of the primary reasons tuberculosis is able to evade the body's immunity is that it __________.
resists digestion by phagocytes
Viruses they are generally _________and only visible with an __________ _______________
small/electron microscope
Algal cells and/or cyanobacterial cells are trapped by this in the meshwork
soredia
the most common source of tinea cruris is _______
spread from feet
One of the virulence factors produced by Group A Streptococcus is __________, which can kill neutrophils, the immune system's first responders.
streptolysin S
AIDS is a what?
syndrome
which of the following is not true of aflatoxins?
that they are produced by penicillium
What part of the United States is endemic for RMSF?
the Appalachian region (North Carolina, Kentucky)
Animal viruses share the same basic replication cycle steps as what? (Lecture 19)
the bacteriophage
A five-year-old girl was admitted to the hospital with a temperature of 103∘F and pain in her right hip. After pus was surgically drained from the hip joint, she was treated with a semisynthetic cephalosporin. He physicians changed the antibiotic regimen after 24 hour cultures of blood and pus revealed the presence of MRSA. On the third day, she suffered respiratory failure and empyema and was placed on mechanical ventilation. She died from pulmonary hemorrhage and pneumonia after five weeks of hospitalization. The girl had been previously healthy with no recent hospitalizations. She had skinned her knee while learning to ride a bicycle two days before admittance to the hospital. What was the most likely choice for the second antibiotic this patient received?
vancomycin
A unicellular fungus is a ________, while masses of long, intertwined fungal _________ are called ________
yeast/hyphae/mycelia
Which of the following do not have hyphae associated with them?
yeasts
How does β-lactamase contribute to the virulence of Staphylococcus spp.?
β-lactamase breaks down penicillin and cephalosporin.
Archaeal cytoplasm similar to bacterial cytoplasm in that they both have
• 70S ribosomes • Fibrous cytoskeleton • Circular DNA
Flagella of archaea
• Consist of basal body, hook, and filament • Numerous differences with bacterial flagella
How Archaeal cytoplasm also differs from bacterial cytoplasm
• Different ribosomal proteins • Different metabolic enzymes to make RNA • Genetic code more similar to eukaryotes
Glycocalyces of Archaea
• Function in the formation of biofilms • Adhere cells to one another and inanimate objects
Archaea features
• Lack true peptidoglycan • Cell membrane lipids (have branched and cyclized hydrocarbon chains). • Their amino acid usage is more similar to eukaryotes than bacteria. • Reproduce by binary fission, budding, or fragmentation • Are cocci, bacilli, spirals, or pleomorphic • Not currently known to cause disease
Methanogens
• Largest group of archaea • Convert carbon dioxide, hydrogen gas, and organic acids to methane gas • Convert organic wastes in pond, lake, and ocean sediments to methane • Some live in colons of animals • One of primary sources of environmental methane • Have produced ~10 trillion tons of methane that is buried in mud on ocean floor.
Fimbriae and Hami of Archaea
• Many archaea have fimbriae. • Some make fimbria-like structures called hami. • Hami function to attach archaea to surfaces
Virus Shapes
• can be classified by virion shape • Three basic types of viral shapes • Helical • Polyhedral • Complex
Protozoan Parasites (Lecture 17)
•Amoebas •Flagellates • Apicomplexa
Penicillum species
- Ascomycetes -rapidly growing molds with highly branched network of multinucleated, septated hyphae that have many branching conidiophores with chains of conidia sprouting from the ends. -they make diverse metabolites. Examples: Penicillum camenberti (used to make Camenbert and Brie cheese), Penicillum roqueforti (used to make Roquefort, Danish blue and Gorgonzola cheese)
saphrobes
- absorb nutrients from the remnants of dead organisms -most fungi are this
All methanogens are ______
- archaea
Large Protein Toxins
- exotoxins - Pore-forming and membrane-disrupting cytolytic toxins, hemolysins - A-B type toxins (AB, AB5, A3B7)
Phaeophyta (brown algae)
- have chlorophylls a and b, carotene, and xanthrophylls. Cell walls have cellulose and alginate (used medicinally).
Aspergillus fumigatus and A. clavatus
- major allergens, associated with allergic bronchopulmonary aspergillosis sinus and respiratory disease
Molds
- multicellular filamentous hyphae. Molds grow primarily as long, tangled filaments (hyphae). -type of fungi
Cyanobacteria of the genus Synecococcus and Prochlorococcus
- responsible for half of the primary oxygen production in oceans.
Yeasts (lecture 16)
- unicellular. Yeasts grow primarily as unicellular forms that form filaments or hyphae (singular: hypha) only during mating (sexual reproduction). -type of fungi
Virus genomes range
-3000 to 2.8 million base pairs
Mycobacterium Mycolic acid
-Acid-resistance -Slow growth -Desiccation-resistance
(Lecture 12) First step for bacteria to colonize
-Adherence (attachment to a surface at a particular site)
Which of the following statements about archaea is true?
-Archaea lack peptidoglycan in their cell walls
In what way are viruses NOT alive?
-Cannot carry out any metabolic pathway -Neither grow nor respond to the environment -Cannot reproduce without the help of a host (they're obligate parasites)
Which type of nucleic acid is NOT found in the genome of viruses?
-Circular, single stranded RNA
What are the minimal components of a virus?
-DNA or RNA and protein
Another characteristic that you want to include in the introduction is bacterial reproduction. Prokaryotic cells have only one chromosome and lack any organelles such as a nucleus, which limits the requirement for numerous cellular processes when a cell divides to form two daughter cells. In both major forms of bacterial reproduction, binary fission and snapping, the single chromosome must replicate so that each daughter cell will carry a complete chromosome. During binary fission, the cell replicates its DNA and each DNA molecule is attached to the cytoplasmic membrane. The growing cell elongates the cytoplasmic membrane, which separates the daughter DNA chromosomes. The formation of a cross wall allows for invagination of the cytoplasmic membrane. The cross wall completely divides daughter cells, which may or may not separate. Snapping division, seen in some Gram-positive bacilli, occurs when only the inner portion of a cell wall is deposited across the dividing cell. This new cross wall puts tension on the outer layer of the old cell wall. Eventually, the outer wall breaks at its weakest point with a snapping movement that tears it most of the way around. The daughter cells can then remain hanging together almost side by side being held by a small remnant of the original outer wall. Choose from the following statements the ones that correctly discuss reproduction using binary fission in a bacterial cell.
-Due to the stretching of the cytoplasmic membrane, both cells will contain a complete genome. -Each daughter cell is an exact copy of the other, both genetically and morphologically.
Entry Step in Replication of Animal Viruses
-Entry of virion into the host cell cytoplasm - and then capsid uncoating (falls apart) and virus genome deposited into cytoplasm
Iron Acquisition
-Free iron is extremely low (10-18 to 10-9M, depending on the body site) due to binding and sequestration by lactoferrin (secreted at mucosal surfaces and in milk), transferrin (made in liver, found in serum), ferritin (intracellular iron storage), and heme (in humans ~70% of total iron is in hemoglobin).
What is a virus?
-Genome: nucleic acid (rna or dna) - Caspid (protective coating) protein or membrane
Mycobacterium Thick peptidoglycan wall
-Gram-positive -Bacillus shape
The symptoms of C. perfringens type A food poisoning usually begin within 6 to 18 hours after the ingestion of contaminated food. The time depends upon the number of bacteria in the food and the amount ingested; thus, the time of onset is dose dependent. Very large doses of bacteria are required to initiate food poisoning because gastric acid kills most bacteria. Organisms surviving the stomach continue to the small intestine, where the presence of bile salts is thought to stimulate sporulation. It is during the in vivo sporulation that the enterotoxin is produced. Rather than being secreted, as are many microbial exotoxins, Clostridium perfringens enterotoxin (CPE) is released into the intestinal lumen by lysis of the vegetative cells during the end stages of sporulation. Most strains of C. perfringens type A food poisoning carry the enterotoxin gene on the bacterial chromosome. Expression of the cpe gene is regulated by sporulation. Large amounts of toxin can be produced during sporulation. Once released into the intestinal lumen, CPE binds to integral membrane proteins called claudins associated with the tight junctions (TJ) of the epithelial cells making up the intestinal villi. The TJ serve as barriers defining the apical and base membrane compartments and function as a gate in regulating permeability across the epithelial layer. Binding of CPE inhibits the absorption of fluid and ions across the epithelium. The CPE forms a complex with claudin on the cell membrane surface, called a small complex. Six of the small complexes on the cell membrane then aggregate to form a larger complex known as a pre-pore that inserts into the cell membrane to make an active pore. Active pore formation results in calcium influx, which leads to cell death due to activation of a proteolytic enzyme known as calpain. The death of intestinal epithelial cells leads to progressive loss of epithelial lining of the villi, causing fluid to be secreted into the lumen of the intestine. An additional effect of CPE is increased myoelectrical activity of the intestine, which leads to the abdominal cramping associated with C. perfringens food poisoning. Which of the findings listed below support the hypothesis?
-Increasing levels of sodium, potassium, bicarbonate, and chloride ions, as well as water, are secreted as toxin concentrations are increased from 25, 50, 100, and 150 units. -Histological observation indicates that morphological alteration and sloughing of epithelial cells occurs up to a maximum of 1000 units. -Protein levels within the ileum loop fluid are increased up to 1000 units of toxin.
Tissue Penetration and Dissemination, Spread in tissues:
-Many pathogenic bacteria produce "spreading factors" that allow them to disseminate from the site of entry into the body to other body sites.
Nutrient Acquisition
-Many pathogens secrete enzymes that break down host macromolecules to release nutrients that are then absorbed or transported into the bacterium.
What type of arrangement occurs when bacilli divide by snapping division?
-Palisades and V-shapes (After dividing by snapping division, daughter cells remain attached and form palisades and V-shapes.)
DNA viruses and diseases they can cause
-Pox viruses (Smallpox) -Herpes Viruses (Herpes / chicken pox (varicella-zoster) / Epstein---Barr (mono) dsDNA -Papilloma viruses (warts) dsDNA -Adenovirus (pinkeye) -Hepadnavirus (hepatitis B) ds and ssDNA genome
Part of the reason for Scott's acne is the overproduction of sebum. Scott's initial instinct is that shutting down production of sebum would be the quickest route to eliminating his acne; however, sebum actually plays an important role in maintaining the skin as a first line of defense against pathogens. Which of the following best describes the role of sebum as a component of the first line of defense?
-Sebum forms a protective layer over the skin. -Sebum helps to keep the pH of the skin low, which inhibits the growth of microorganisms.
Disease research and epidemiology bring together many different facets to help us better understand disease pathology and spread. Which of the following statements are true?
-Some pathogens are able to cause disease within a host without penetrating the body. -The interactions that occur between a microbe and host influence the evolution of both. -Bacterial exotoxins can be altered to create toxoids, which can be used to produce protective immunity in a host.
How do archaeal ribosomes differ the most from bacterial ribosomes?
-The RNA in archaeal ribosomes differ from those in bacteria.
You decide that the introduction should also discuss the extremophiles that are referred to as the archaea. These single-cell organisms are considered "extremophiles" due to their ability to survive and reproduce in environmental conditions that would be hostile for most living organisms. Archaea species have been isolated from highly acidic sulfur springs, ocean floor thermal vents with temperatures that exceed boiling, and subarctic ice well below freezing. While still considered to be prokaryotic, the archaea have numerous differences that place them apart from the bacteria. Choose the characteristics that separate the archaea from other prokaryotic cells.
-The cytoplasmic membrane lipids of archaea have branched or ringform hydrocarbon chains. -Archaea lack true peptidoglycan in their cell walls.
How can viruses be good
-There are viruses that kill antibiotic resistant bacteria -Viruses positively influence the carbon cycle and many other processes (i.e. they influence your microbiota) -Enhanced Biotechnology (Crispr Cas, phage display, etc)
Why do doctors caution patients who are pregnant to avoid deli meats, cold cuts, and soft cheeses?
-These foods are soft and easy for the bacteria to spread throughout, the Listeria bacteria can easily grow in the uncooked food stored in the fridge
Wanda recently started a job at a local free women's health clinic. She took this job because she was raised in a family that struggled financially, so the free clinics were an important aspect of her childhood health care and she wants to give back to her community. Although the clinic sees women for a variety of issues, the most common visits are related to family planning and prenatal care. Because of this, Wanda is reading about sexually transmitted infections in order to be better at her job. From her school studies, Wanda is familiar with the infectious agent, symptoms, and treatment of many sexually transmitted infections, but she is particularly interested in the statistics from the local Health Department about STI rates in the area. When Wanda reads that C. trachomatis is the most common STI in the region, she decides to investigate the Chlamydia group of bacteria further. Which of the following are true for the Chlamydia group of bacteria?
-They are all intracellular parasites -They are all very small in size.
In what way are viruses alive?
-They replicate (make more of themselves) -Have extracellular and intracellular state -Cause infections of humans, animals, plants, bacteria, and archaea. -Cause most of the diseases that plague the industrialized world -They evolve over time
Which of the following are properties of exotoxins?
-Very small amounts of exotoxin can be lethal. -Exotoxins target specific cellular structures or molecules. -Exotoxins are protein molecules.
What is the most abundant biological entities on the planet (Lecture 18)
-Viruses
Collagenases, elastases, and other proteases
-act as "meat tenderizers" that degrade connective tissue matrix proteins. Some also degrade antibodies and complement proteins
what do viruses infect?
-all forms of life, including other viruses
Blastomyces species
-are dimorphic fungi that exist in soil as a filamentous form with conidia (spores) that form directly on the wall of the hyphae (no fruiting body forms). -the spores are inhaled and then germinate at 37 degrees celsius into the yeast form in lungs. They can also enter through cuts and abrasions. -Infection is usually cleared in 2-3 weeks. Systemic infections (blastomycosis) manifests as skin lesions (blisters), bone lesions (joint/bone pain) and/or acute respiratory distress syndrome (ARDS).-
Neisseria strains
-are nonmotile and typically arranged as diplococci -Gram-negative -fimbriae
Histoplasma species
-ascomycetes -thermally dimorphic fungi that grow as a brownish mycelium externally and as a yeast form degrees celsius (in body). -__________ capsulatum is endemic in the Midwest of USA where it is associated with dry, dusty soil and bird and bat droppings. -most infections are silent with no clinical manifestations, but if symptoms occur they are flu-like. -In immunocompromised patients disseminated disease is fatal unless treated.
what do microbial viruses infect?
-bacteria and archaea
Motility Test
-bacteria are stabbed into soft agar medium containing red indicator dye. Bacterial growth acidifies the medium (red). If they are motile, then they will swim all over the medium and the culture looks homogeneously cloudy. If they are not motile, then they remain near the stab line.
siderophores (catechols or hydroxamates)
-bacteria secretions that chelate iron with very high affinity.
__________are the environmental reservoir for infection with cryptococcus neoformans
-birds
Yeasts reproduce asexually by budding to form this
-blastosphere
What can Virus genomes NOT contain
-both DNA or RNA, they can only have one or the other.
How does phage in the mucus protect human cells?
-by killing the bacterial pathogens.
Bacterial Attachment
-can be nonspecific, mostly based on hydrophobic interactions or on charge interactions, or it can be highly specific and dependent on tight and specific ligand-binding to its cognate receptor
Which of the following statements about Candida is false?
-candida can be easily treated with topical antifungals in immunocompromised individuals
In a section that will be a brief survey of the prokaryotic bacteria, you want to give an overview of the multiple groups of bacteria and representative bacteria within each group. The groupings have been developed based on many characteristics of the bacterial cells and attempt to group together different species with similar cellular characteristics. Cellular morphology, cell wall composition, and metabolism have historically been used as means to roughly group bacteria together into different classes and genera. Current technologies have been expanding and reorganizing these groupings based on lipid content and genomic characterizations. Which of the following characteristics would NOT be used to aid in classifying a newly discovered bacterial species?
-cellular size
what are most fungal cell walls are made of?
-chitin (acetylglucosamine polymers) and galactomannans.
proviruses (integrated virus)
-chronically produced (without killing the cell) and used as a weapons to kill other susceptible hosts in the population in order to enhance fitness of the resistant host -harbored by some cells
Phospholipases
-cleave lipids in membrane which lyse host cells, releasing contents
neuraminidases/sialidases
-cleave sialic acid residues from host cell glycolipids or glycoproteins
Lichens
-composed of a community of ascomycete, basidiomycete, and a photosynthetic cyanobacterium or alga.
All archaea have ________ ___________
-cytoplasmic membranes. • Maintain electrical and chemical gradients • Control import and export of substances from the cell
DNases
-degrade DNA present in pus at the infection site, which is made viscous by the DNA released by lysed host cells. DNases thin out the pus, making it easier for the pathogen to move and disseminate.
Nucleases
-degrade DNA/RNA in pus that is released from damaged host cells
Plasminogen activator-like proteases
-degrade fibrin clots and allow bacteria to escape from blood clots. Other bacteria produce and secrete proteases, such as streptokinase secreted by Streptococcus species, that cleave and activate host serine protease plasminogen activator, which in turn degrades fibrin clots by converting plasminogen into plasmin.
Proteases
-degrade proteins (e.g., collagenases, elastases act as "meat tenderizers" that degrade connective tissue matrix proteins, IgA or IgG proteases cleave Abs).
Replication of Animal viruses: Release
-delivery of newly made virus particles into the world so that the entire process can be repeated -capsid goes to cell membrane and "blows bubbles" of plasma membrane, it pinches of, detaches from cell, goes back and repeats process again
Mycolactones are polyketide
-derived macrolides (lipid-like toxins)
Trichophyton species
-dimorphic fungi that exist in soil and moist environments as a filamentous form with conidia (spores) that form directly on the wall of the hyphae (no fruiting body forms). -associated infections: athlete's foot and jock itch
Candida species
-diploid fungi that grow as yeast and filamentous (with hyphae) forms. -the fungi undergo a reversible process of phenotypic switching, in which environmental regulation of genes and spontaneous gene switching (turning on/off) generates different morphologies -part of normal microbiota in ~80% of human population, but is also the causal agent of opportunistic oral and genital, and sometimes systemic infections in humans.
How can viruses be bad
-ebola, flu, HIV, etc. -Allow transfer of genetic material That can provide toxins to bacteria or cause cancers.
Bacteriophages
-encode factors required for protection in a symbiotic mutualism
Coccidioides immitis location
-endemic in desert areas of Southwest USA.
Blastomyces dermatidis
-endemic in the Midwest of USA, -causes skin & bone lesions in systemic infections, and chronic pneumonia, associated with immune compromised and AIDS patients (mortality rate ~40%). -associated with dusty soils near barns or sheds and bird droppings
Small Molecule Toxins
-endotoxins (lipopolysaccharide lipid A, pertussis tracheal cytotoxin), lipid-derived toxins (mycobacterial mycolactones) -compounds, either secondary metabolites or bacterial membrane components, made by bacteria that have toxic effects on host cells.
Small Peptide Toxins
-enterotoxins (toxic shock syndrome toxin), superantigens
Toxic Effector Proteins
-enzymes delivered into host cells by specialized bacterial secretion systems that cause toxic effects
Cytolytic toxins
-enzymes that degrade the host membrane by hydrolyzing membrane phospholipids. __________ __________are usually called phospholipases (hydrolyze phospholipids), hemolysins (lyse RBCs), or cytolysins (cytotoxic to cells).
Algae (Lecture 15)
-eukaryotic photoautotrophs that are mostly aquatic (marine algae have holdfasts to anchor to surfaces). They can be unicellular or simple multicellular, but some can form communities
Lipid A triggers what?
-fever, vasodilation, inflammation, shock
Some adherent bacteria do this
-generate two kinds of daughter cells: one stationary and the other mobile.
Cryptococcus neoformans
-grow as a yeast (unicellular) and replicate by budding, but make filamentous forms (hyphae) during mating (sexual reproduction) and eventually generate basidiospores at the end of the hyphae before producing mature spores. -mostly effects the immune compromised
Pili (single: pilus)/fimbriae (single: fimbria)
-have adhesins at their tips that mediate the attachment to surfaces.
Rhodophyta (red algae)
-have red accessory pigment phycoerythrin. Cell walls have agar and carrageenan (used commercially as thickening agents).
Which of the following processes is not part of the lysogenic cycle of bacteriophages?
-host-cell lysis
Among the virulence factors produced by Staphylococcus aureus are hemolysin, coagulase, hyaluronidase, and enterotoxin. Which of these factors contribute(s) to the ability of S. aureus to invade the body?
-hyaluronidase
mycelia
-hyphae form these compact tufts
Apicomplexans
-invasive protozoan parasites of the phylum ---_______________ that are characterized by having a complex of organelles at their apical tips that are used for penetrating host cells. -Some are transmitted via ingestion and cause localized infection, while others are vectorborne and cause systemic diseases. -e.g. Toxoplasma gondii is an invasive ____________ that infects humans and most animals and causes toxoplasmosis.
(Lecture 13)A strain of the Gram-negative bacterium Neisseria gonorrheae, has a mutation that has caused the bacteria to lose the ability to produce fimbriae and so it has become less avirulent as a consequence. What function has this pathogen lost?
-it lost the ability to adhere to a cell
A toxin common to most Gram-negative bacteria is
-lipid A
Gram-negative bacterial cell wall contains_____
-lipid A, also known as endotoxin
Listeria virulence is directly related to its ability to
-live within cells and thus avoid exposure to the immune system of its host
Suppose you have two A-B type toxins, A-B and A'-B'. A-B binds specifically to neurons and blocks protein synthesis to kill the nerve cells. A'-B' binds specifically to intestinal cells and blocks Na2+ uptake to cause diarrhea. What would injection of a hybrid toxin, A'-B, into an animal do to its muscle cells?
-nothing would happen
Replication of Animal viruses: Assembly
-organization of all the virus parts to make new viruses -for dsDNA viruses like herpes and papilloma (wart) viruses.
Pore-forming toxins
-poke holes in host membranes to form transmembrane channels, resulting in irreversible osmotic swelling and lysis of the cell. These toxins are often called lysins or hemolysins.
Adhesion to specific cells or tissues leads the bacteria to have cell or tissue tropism
-preference for growth at that location in the body or surface type.
superantigens (SAg)
-produce peptide toxins -over-stimulate host inflammatory responses that results in toxic shock (a.k.a. cytokine storm).
Noninvasive flagellates
-protozoan parasites that are characterized by having two nuclei, each with 4 associated flagella for motility. They lacking mitochondria and a Golgi apparatus. -e.g. Trichomonas vaginalis
Aspergillus species
-rapidly growing, aerobic molds with branching septate hyphae and characteristic conidia on the conidiophore. e.g. aflatoxin - hepatotoxic causing cirrhosis of liver and one of most potent known carcinogens
AB type toxins are large proteins comprised of 2 functional parts: (1) An part (domain or subunit) with toxic (usually enzymatic) activity
-responsible for the observed cellular outcomes.
Endotoxins
-small molecule toxin -are toxic membrane components (LPS, LTA, PG) from bacteria that are released into the medium when the bacteria are lysed. They cause toxic effects on host cells and tissues, often leading to toxic shock and death.
Amoebas
-soft-bodied (change shapes making pseudopods as they move) protozoans that are mostly free living (but sometimes go through cyst stage). Most live in fresh water
Toxins
-some pathogens produce and secrete toxins (e.g., pore-forming hemolysins) that disrupt host cells to release cytosolic contents (nutrients and iron)
Basidiomycetes
-species are encapsulated yeast that can live in both plants and animals. -found in soil of urban environments -grows actively in pigeon droppings -these fungi grow as a yeast (unicellular) - replicate by budding, -make hyphae during mating -generate basidiospores at the end of the hyphae before producing mature spores -saphrobes
RNA Viruses are the only biological agents that what?
-store genetic information in RNA molecules
It is common for DNA virus genomes to enter the nucleus for ___________ to occur.
-synthesis
The period of time required to complete the lytic cycle is called
-the burst time
What is the meaning of the word pyogenes?
-the localized, pus-filled lesions are caused by group A streptococci (Streptococcus pyogenes).
Metagenomics
-the study of genetic material recovered directly from environmental samples.
What allows archaea to live in extreme enviornments
-their cell structure and metabolism
Although the proteins they transfer may be different, the type 3 secretion systems of Escherichia coli, Salmonella, Shigella, and Yersinia function similarly in that they _______.
-they transfer bacterial proteins from the bacterium into the host cell.
What is NOT a reason an animal virus would want to have a host cell envelope around its capsid?
-to avoid the host cell cytoplasm
Invasive flagellates
-transmitted via insects (vector-borne). They also have unsheathed or membrane-sheathed flagella that enable mobility. They replicate via fission. -Trypanosoma brucei (transmitted by the tsetse fly) -Leischmania species (transmitted by female Phlebotomus sand)
Bacteriophages are part of our microbiome?
-true
• Dimorphic fungi with two forms
-usually (but not always) at ambient temperatures (~25 degrees celsius (room temp) ) they grow as multicellular (multinuclear), filamentous molds, but at body temperatures (37 degrees celsius) they convert into unicellular pathogenic yeast forms
Which statement MOST accurately describes lytic viral replication?
-viral replication usually results in the death and lysis of the host cell.
what are the most most diverse and uncharacterized components of the major ecosystems on Earth and have intricate roles in ecosystem function that go far beyond simple predator-prey dynamics
-viruses
how do animal viruses to attach to host cell receptors?
-with glycoprotein spikes
Pneumocystis species
-yeast-like fungi that have complex life cycles taking place entirely in the alveoli of the lung. -Transmission is person-to-person by air droplets.
Bacteriophage Replication (lysogenic cycle)
1) attachment 2) entry 3) Integration of the virus genome (prophage) into the host genome 4) Lysogeny. Normal cell division replicates host and integrated virus genomes. 5) Induction. Normal cell division replicates host and integrated virus genomes. 6) Synthesis 7) Assembly 8) Release
During the synthesis phase of a double-stranded DNA animal virus depicted below, correctly name the host-cell processes that are hijacked by the virus.
1)Transcription, 2) Translation, 3) Replication
HIV life-cycle
1. Attachment (binding of the virus to the host target cell). 2. Entry (transfer of the virus Genome into the host target cell). 4. Assembly (organization of all the virus parts to make new viruses). 5. Release (delivery of newly made virus particles into the outside world so that the entire process can be repeated). 3. Synthesis (using the host machinery to make all of the parts of the
Attachment Steps
1. Loose attachment, usually mediated by pili, fimbriae, or fibrillar adhesins. 2. Tight (intimate) attachment, usually mediated by surface protein afimbrial adhesins.
RMSF results from the interactions that occur between the R. rickettsii pathogen and the host. The infection results from a coordinated series of events that ultimately result in disease.
1.tick bites transmit 2.R.rickettsii travels throughout the body 3.R.rickettsii invades endothelial cell 4.R.rickettsii multiplies 5.blood begins to escape from vessel 6.symptom
Viruses outnumber microbial cells by _________ (ratio) in most environments.
10:1
Adhesins (attachment proteins)
:bacterial cell-surface components that facilitate adhesion or attachment to surfaces or to proteins or sugars on other bacterial or eukaryotic cells
Why don't archaea appear to cause pathogenesis in humans? A. We haven't found one yet. B. They do cause pathogenesis, we just don't know which diseases yet. C. Antibiotics that kill bacteria also kill archaea. D. Archaea live in extreme environments that humans can't survive.
A & B: -We haven't found one yet. -They do cause pathogenesis, we just don't know which diseases yet.
In which of the following cases would you suspect wound botulism?
A person injures herself while gardening. Four days later she begins to feel weak and dizzy, with blurred vision and progressive paralysis.
Botulinum toxin is a ____________________ that binds to the synapses of motor neurons and prevents the release of the _________________ resulting in temporary ______________________ paralysis of associated muscle
AB-type neurotoxin, acetylcholine neurotransmitter, flaccid
Which of the following is definitively diagnostic for tuberculosis?
Acid-fast stain of sputum
Rickettsia rickettsii is a gram-negative, obligate intracellular pathogen. Which of the following statements about the R. rickettsii life cycle is FALSE?
After entering a host, R. rickettsii multiplies to levels high enough to successfully invade cells and establish an infection.
What is listeriolysin O?
An enzyme breaks the bacteria free from the phagosome.
In the case of gastrointestinal disease, how can an intoxication be distinguished from an infection?
An intoxication is usually apparent shortly after ingestion, while an infection takes longer.
Although cholera can be treated with antibiotics, data suggest that antibiotic treatment alone is NOT the most effective therapy. Which of the following statements describes the most likely reason for supplementing antibiotic therapy?
Antibiotic therapy addresses only the growth of V. cholerae; it doesn't address the extreme dehydration suffered by a person infected with V. cholerae.
Why are antimicrobial drugs of limited usefulness in Bacillus anthracis infections?
Antimicrobial drugs are unable to neutralize anthrax toxin.
which of the following are not eukaryotic microbes?
Archaea
How does coagulase facilitate bacterial virulence?
Bacteria can hide in the protein clots that result from the action of coagulase.
Gram-negative bacteria in the genus ________ prey on other Gram-negative bacteria.
Bdellovibrio
Based on its Gram status, why are penicillin and other beta-lactam antibiotics effective against Streptococcus pneumoniae?
Beta lactam antibiotics are effective against Streptococcus pneumoniae because it is a Gram positive organism and does not have an outer membrane.
Two patients - a woman and her husband, ages 23 and 22, respectively - arrive at the health clinic one morning. They report having had severe abdominal cramps, grossly bloody diarrhea, nausea, and fever for 48 hours. Cultures of stool samples grown under microaerophilic, capneic conditions contain comma-shaped, Gram-negative bacilli. Both the patients are lactovegetarians and report being part of a "cow leasing" program at a local dairy in which patrons lease part of a cow's milk production so that they can drink natural, whole, raw milk. The couple devised the program so that they and several neighbors could circumvent state regulations prohibiting the sale of unpasteurized milk. Investigators obtained and cultured a milk sample from the dairy's bulk milk tank. What is the most likely cause of this couple's disease?
Campylobacter jejuni
Which opportunistic fungus is characterized by pseudohyphae?
Candida
How are patients typically infected with listeriosis?
Contaminated food or drink
Which of the following is not usually used for treating tuberculosis?
Erythromycin
__________ is the treatment of choice for C. trachomatis.
Erythromycin
How are fungal and animal cytoplasmic membranes different from each other?
Fungal cytoplasmic membranes contain ergosterol, while animal cytoplasmic membranes contain cholesterol.
What is the difference between Gram-positive bacteria and mycoplasmas?
Gram-positive bacteria have thick cell walls, while mycoplasmas lack cell walls.
Mycobacterium DNA structure
High G+C
The BCG vaccine is available to immunize people against tuberculosis. Had Lance been vaccinated, he would not have been concerned about becoming infected on the airplane. Why was he NOT vaccinated?
Immunized patients have a positive skin reaction when tested, even if they have not been infected with Mycobacterium tuberculosis. Such "false positive results" hinder the work of epidemiologists trying to track the spread of the disease.
The pneumococcal vaccine was made using the purified capsular material from 23 common strains of Streptococcus pneumoniae, but it is not effective against all strains. Why is this?
It cannot cover all the strains of Streptococcus pneumoniae because not all strains have the same antigens on their surface.
Why is necrotizing fasciitis so difficult to prevent?
It is part of the normal microbiota.
Which of the following bacterial genera includes species that protect areas of the body such as the intestinal tract and the vagina from invasion by pathogens?
Lactobacillus
__________ is an antiphagocytic factor and helps S. pyogenes attach to nose and throat cells.
M protein
Which of the following bacterial genera plays an important role in environmental nitrogen cycles?
Nitrobacter, Rhizobium, and Azospirillum
Are Clostridium botulinum vegetative cells required to be present for foodborne botulism to occur?
No, foodborne botulism is caused by the botulinum toxin produced by the bacteria, not the bacteria themselves.
Which of the following is NOT a reason archaea thrive in extreme environments?
Nuclear composition
Acne is the result of the inflammatory response. In this case, the inflammation is resulting in acne that is very painful (physically and emotionally) for Scott. However, inflammation is a critical component of a normal immune response. What are the main functions of the inflammatory response?
Repairing tissue damage resulting from inflammation Destroying and eliminating the invading pathogen "walling off" the site of injury or infection
What enzyme allows HIV to go against the "Central Dogma" of molecular biology?
Reverse Transcriptase
Which of the following lists the criteria for a diagnosis of Staphylococcus aureus infection?
Staphylococcus aureus cultures are coagulase positive, catalase positive, yellow colonies that are composed of Gram-positive cocci.
Which of the following bacteria is the primary cause of necrotizing fasciitis?
Streptococcus pyogenes
Which genus of high G + C Gram-positive bacteria synthesize antimicrobials such as chloramphenicol, erythromycin, and tetracycline?
Streptomyces
Why do male teens have more acne than male adults?
The P. acnes bacteria overgrow during puberty when sebum is abundant due to higher testosterone levels, particularly in males
How is the dormant form of Rickettsia rickettsii activated?
The bacteria are activated after the tick feeds on a host for several hours.
Strains of Streptococcus pneumoniae can cause disease only when a capsule is present. Why is the presence of a capsule considered a virulence factor?
The capsule prevents the bacterium from being digested after endocytosis in the cells of the host.
Which of the following is an advantage for a bacterium having the ability to invade and reside inside host cells?
The host cytosol is rich in nutrients, if access can be gained by the bacteria
Streptococcus pneumoniae was originally named Diplococcus pneumoniae. Why was the genus name Diplococcus originally given to this organism?
The prefix "di-" means two, and these organisms are usually found in pairs under the microscope.
Which of the following is CORRECT about the prokaryotes known as deeply branching bacteria?
They are commonly found in acidic, anaerobic conditions.
Which of the following is NOT a property of Lactobacilli?
They are members of the high G + C Gram-positive bacteria
Some studies have indicated that the ID50 for Vibrio cholerae can be as high as 108 organisms. Which of the following most likely explains the requirement for this relatively high ID50?
To establish infection, V. cholerae must survive the host immune response and the acidic environment of the stomach.
How do clinicians primarily screen for tuberculosis in patients?
Tuberculin skin test
Why don't we currently have a cure for HIV?
Vaccine must generate antibodies and cytotoxic T cells Numerous HIV variants within an individual and in populations HIV can spread directly from cell to cell HIV infects cells important to combating infections Vaccine testing involves ethical and medical concerns
What is empyema?
a pocket of pus in between the lung and the inner surface of the chest wall.
This Cough Can Kill A jumbo jet finally takes off from the airport in Johannesburg, South Africa, and Lance relaxes in his business-class seat. The next stop, 16 hours later, will be Atlanta, Georgia. Lance has just spent six weeks interning with a South African law firm that specializes in human rights issues. His work took him to clients living in crowded conditions in several poor townships. Now Lance's thoughts turn to the upcoming fall term, when he will practically live in a study carrel, law books his constant companions. The deep coughing of a woman sitting beside him interrupts his reverie. He glances at her; she is thin and huddles against the armrest, looking pale and tired. She often rubs her chest as if it hurts. When the flight attendant offers the woman something to eat and drink, she turns everything down. Her loud, incessant coughing continues for the entire flight, interrupting Lance's sleep. Four weeks later, Lance opens a letter from the state department of health and learns that he may have breathed in a potentially deadly bacterium on that flight from South Africa. The letter advises Lance to have a physician administer a skin test to determine if he has been infected, but it also tells him that he must wait eight more weeks before being tested. An appropriately stained smear was prepared of a sputum specimen obtained from the sick woman on Lance's flight. Using oil-immersion magnification on your microscope, what would you observe that would aid in the diagnosis of tuberculosis?
acid-fast rods
Listeria Movement
actin-based motility - comet-tail propulsion from cell to cell
The ability of Vibrio cholerae to cause disease depends on a number of factors. Which of the following are general requirements for any organism to cause disease within a host?
adherence to host tissues evasion of host defenses gaining access to the host via a portal of entry
Mycobacterium tuberculosis is considered a(n) __________.
aerobe
The deadliest mushroom toxin is produced by
amanita phalloides
What is the "gold standard" for treatment of histoplasmosis?
amphotericin B
Key differences between the replication cycles of bacterial animal viruses: * Presence of envelope around some viruses * Eukaryotic nature of animal cells (i.e. nucleus, organelles, etc.) * Lack of cell wall in animal cells
animal vriuses have glycoprotein spikes to attach to host cell receptors
Opportunistic fungi that can be pathogens in some people ____________
are part of the natural microbiota for many individuals
Fungal hyphae that lack cross walls are called ________ hyphae.
aseptate
Bacteriophage Replication (lytic cycle)
bacteriophage T4 undergoes this 1. Attachment (binding of the virus to the host target cell). 2. Entry (transfer of the virus genome into the host target cell). 3. Synthesis (using the host machinery to make all of the parts of the virus). 4. Assembly (organization of all the virus parts to make new viruses). 5. Release (release of newly made virus particles into the outside world by lysing the host cell so that the entire process can be repeated).
Toxins are the sole symptoms of
botulism from Clostridia (causes paralyisis)
gonorrhea treatment
broad-spectrum intramuscular cephalosporins (e.g., ceftriaxone) plus azithromycin or doxycycline
In which of the following methods of prokaryotic reproduction does the parental cell remain intact after the reproduction event to continue the process?
budding
Although many people along the Mississippi, Missouri and Ohio River valleys have been exposed and test positive for histoplasmosis, most (95%) are asymptomatic. How do they clear the organism from their bodies?
cell-mediated immunity
Hyaluronidases
degrade the charged polysaccharide hyaluronic acid found in connective tissue, thereby degrading the extracellular matrix and allowing spread along tissue planes.
Ringworm is caused by __________________
dermatophytes growing in the outer dead tissue layers of the skin.
All truly pathogenic fungi exist in the environment as molds but grow in the body as spherical yeasts. This trait is known as __________
dimorphism
Taxis
directional Movement in Response to Stimulus
AB type toxins are large proteins comprised of 2 functional parts: (2) A part (domain or subunit) that binds to receptors on the surface of host cells and mediates the process of intoxication:
entry (cell uptake), trafficking (movement in vesicles to various cellular compartments such as late endosomes) and getting the A part into the host cell cytosol (translocation of A part across the vesicle membrane), where the A part can gain access to its target substrate and modify it.
Virulence factors encoded in prophages can improve the _________of the bacterial host
fitness
mycoses
fungal infections in plants and animals
Many mycoses are difficult to treat because______
fungi are biochemically similar to humans (both are eukaryotes)
Chrysophyta (golden, yellow-green algae)
have chlorophylls a and b and carotene. Group also includes diatoms, water molds (marine phytoplankton). These are a major source of the world's oxygen supply.
Chloraphyta (green algae)
have chlorophylls a and b.
