Micro Exam 2
Reservoir definition
Provide the correct conditions and nutrients for the pathogen to replicate and survive and are usually not harmed by the pathogen thus it is not always apparent what the reservoir is for a particular pathogen
Class of organisms that would display optimal growth in the following environments: in a refrigerator (4 degrees C)
Psychrophile
Class of organisms that would display optimal growth in the following environments: in the ocean along the coast of Antarctica
Psychrophile
Temp Psychrophiles/psychrotrophs grow
Psychrophile prefer a cold enviroent while psychrotrophs (associated with food spoilage) prefer a more moderate temp range
Class of organisms that would display optimal growth in the following environments: in a bowl of macaroni salad at a picnic (22 degrees C)
Psychrotroph
How is antibiotic resistance gene used in a plasmid for gene cloning
R plasmid which may contain genes that code for enzymes that can modify to inactivate a drug
Process of transcription/translation in prokaryotes
RNA polymerase binds to the promoter and DNA unwinds at the beginning of a gene, RNA is synthesized by complementary base pairing of free nucleotides with the nucleotide bases on the template strand of DNA, the site of synthesis moves along DNA: DNA that has been transcribed rewinds. Transcription reaches the terminator, RNA and RNA polymerase are released, and the DNA helix re-forms
Which tube is representative of an obligate aerobe?
Tube 1
Which tube is representative of an obligate anaerobe?
Tube 2
Which tube is representative of a facultative anaerobe?
Tube 3
Which tube is representative of an aero tolerant microorganism?
Tube 5
One ________ is the division of one cell into two.
generation
All of the following are used by bacteria to attach to host cells EXCEPT:
Coagulase
Which of the following statements is FALSE?
Coagulase destroys blood clots
Importance of virulence factors: are enzymes
Coagulase, kinases, hyaluronidase, collagenase, IgA proteases
Can result in the conversion of a cell from F- to F+
Conjugation
Delivers a plasmid to an F- cell
Conjugation
Requires contact between bacterial cells.
Conjugation
Endemic diseases
Constantly present in a population
Direct transmission of a pathogen requires:
Contact
What is a method by which you could verify the number of bacteria (cfus/mL) in the samples in the above question? Explain your reasoning for the method you choose.
Could use the plate count or serial dilution method so we can isolate the colonies and dilute them to be able to see how many colonies grow when it's diluted.
How to do the equation
2n*initial #
Generation time formula
2n*initial number of bacteria=total number of bacteria present after n generations
The enzymes involved in transcription and DNA replication read nucleotides in the _____________ direction.
3'-5'
The enzymes involved in transcription and DNA replication build nucleotides in the _________ direction.
5'-3'
Transmission of a pathogen by a flea bite occurs through:
A biological vector
Direct methods of measuring cell growth: plate counts
A culture is serially diluted and then placed onto nutrient media to allow for the growth of colonies. A math equation is used to relate the number of colonies back to the original culture. ONLY COUNTS LIVE CELLS
Turbidity (indirect method of measuring cell growth)
A light shown through the sample to determine the absorption of the sample, the higher the amount of organism, the more light will be absorbed
A fly lands on a contaminated surface then onto food consumed by a host. The fly is an example of:
A mechanical vector
Temp mesophiles grow
A mid level temp
Briefly state how the following terms are similar and how they are different: reservoir and host
A reservoir is an inanimate object like water/air that contain a disease and can spread to people. A host is what viruses and arterial use to infect someone who they can live inside of. Both are used to harbor bacteria and make the disease stronger.
Direct methods of measuring cell growth: filtration
A sample is poured through a filter to collect the bacteria then the filter is placed onto a plate contains the appropriate media to encourage the growth of the organism
An organism needs phosphate in order to build:
ATP and nucleic acids
Epidemic diseases
Acquired by many people in a given area in a short time
A healthcare-associated infection (traditionally known as a nosocomial infection) is:
Acquired during hospitalization
Nosocomial infection
Acquired while receiving treatment in a healthcare facility
Two important proteins involved in the division of bacterial cells are:
Actin and myosin
Describe the processes of polymerase chain reaction (PCR)
Add primers, nucleotides, and DNA polymerase Incubate 94c for 1 min, will separate the strands Incubate at 60c for 1 min, allows primers to attach to single-stranded DNA Incubate at 72c for 1 min, DNA polymerase copies the target DNA Repeat the cycle of heating and cooling to make more copies of target DNA
Briefly state how the following terms are similar and how they are different: airborne versus droplet transmission
Airborne transmission is from microbes that stick onto dust particles and droplet transmission is from sneezing or coughing as droplets of spit leave your mouth. Both can transmit diseases and cause illness.
RNA sequencing
Allow you to look at all the mRNA that have been produced within an organism
Sanger sequencing
Allows you to sequence one gene
Compare conjugation between F+ x F-
An F+ cell will produce a mating bridge that allows for the transfer of a copy of the conjugation plasmid to an F- cell
Possible consequences of base substitution (point) mutations: silent mutation
An abnormal gene is transcribed in host cell, siRNA binds mRNA. RISC breaks down the RNA complex and no protein expression occurs
Which one of the following does NOT directly contribute to the incidence of healthcare-associated infections?
Antibiotic resistance
Mechanical vectors
Arthropods carries pathogen on its feet, then land on something like food then will be consumed by host
Use the following figure to determine the concentration of the original culture in CPU/mL
Cfu*dilution over mL plated
Consequences of a frame shift mutation
Changes the reading frame of the codons by the ribosome
Noncommunicable disease
Not transmissible through contact with an infected individual but rather come either from an opportunistic pathogen or from the entry of the pathogen from outside the body where it causes disease
Process of transduction
Bacteriophage will accidentally incorporate host DNA rather than viral DNA. This bacteriophage will the inject its host DNA into a recipient cell thus introducing new genetic information to this host cell
If an inserted gene interprets the function of the LacZ gene on the pUC19 plasmid, the transformed colonies will be _______________.
Blue
In which of the following patterns of disease does t he patient experience no signs of symptoms?
Both incubation and convalescence
mutualism
Both organisms benefit
How can the microbiome prevent the activity of pathogens
By directly competing with incoming pathogens for nutrients and other required components. Can produce and release compounds into its surroundings that can repel invading microbes
Briefly state how the following terms are similar and how they are different: communicable versus Noncommunicable disease
Communicable disease is something you can pass onto others like the flu or a cold. Noncommunicable disease is something that cannot be transmitted to person to person, it is not contagious like food poisoning and botulism poisoning. Both are ways of making someone sick and cause discomfort.
RT-PCR
Can be used to look for certain RNAs
Oxygen requirements/tolerance: microaerophiles
Can grow in the presence of low level of oxygen. Atmospheric oxygen levels are toxic to these organisms. They also have oxygen sensitive enzymes and molecules that are harmed by higher levels of oxygen
What is the advantage to an organism in a biofilm?
Can make antibiotic treatment difficult and species of bacteria found in a biofilm is 1000x more tolerant to anti microbial substance
Oxygen requirements/tolerance: obligate aerobes
Can only produce energy through aerobic cellular respiration
Next-gen sequencing
Can sequence the entire genome
Oxygen requirements/tolerance: obligate anaerobes
Cannot use oxygen for respiration purposes and lack the necessary enzymes to breakdown some of the harmful forms of a a molecular oxygen. Cannot be in the presence of molecular oxygen
Importance of virulence factors: Can prevent phagocytosis
Capsules
Virulence factors can include:
Capsules, exotoxins, and endotoxins (all of the above)
Human reservoir
Carriers may have inapparent infections or latent diseases
Direct methods of measuring cell growth: Direct microscopic count of bacteria w/ a Petroff-Hausser cell counter
Cells can be counted in certain numbers of squares present on the slides, a math equation is used to determine the number of organisms found in the sample. CANNOT TELL IF ALIVE OR DEAD
Assign the appropriate phase to the description of activity within a culture: death of cells is occurring after than the growth of cells
Death phase
Assign the appropriate phase to the description of activity within a culture: nutrients have been exhausted and toxins have built up to high levels
Death phase
Phases of a microbial growth curve #4
Death phase: population numbers are decreasing at a logarithmic rate, organisms are running out of nutrients and waste products are building up which results in an overall decrease in the population numbers
Basic process and use of DNA sequencing
Determining the exact sequence of nucleotides. Encodes the biological information that cells use to develop and operate
Acute disease
Develops quickly but lasts for a short time
Chronic disease
Develops slowly and may continue for long periods of time or recurs for long periods of time
Notifiable infectious diseases
Diseases in which physicians are required to report occurrence
Emerging infection
Diseases that are new, increasing in incidence, or showing a potential to increase in the near future
Oxygen requirements/tolerance: aerotolerant anaerobes
Do not use oxygen but are not harmed by oxygen, they will often have superoxide dismutase to help deal with any reactive oxygen species that might develop in the presence of oxygen
A cold transmitted by a sneeze is an example of:
Droplet transmission
a biofilm can be composed of:
Multiple different species of both eukaryotes and prokaryotes
A sudden increase in the number of influenza cases in the United States would be considered:
Endemic
Rhinoviruses, which cause the common cold in the United States, can be thought of as a/an:
Endemic
Importance of virulence factors: Can lead to overstimulation of the inflammatory system
Endotoxins
Briefly state how the following terms are similar and how they are different: Endotoxin and Exotoxins
Exotoxin makes the microbes inside itself and releases them. Endotoxins only release when they multiply, from gram- bacteria, causing microscopic holes in cell for it to leave. Both can cause harm and septic shock.
Importance of virulence factors: Have both binding and enzyme activity
Exotoxins (include A-B toxins)
How nosocomial infection occur
Exposed to microbes through an invasive procedure
An Hfr can transfer its genetic material to a(n):
F- cell
Process of transformation
Naked DNA is taken up either naturally by an organism or through manipulation of the bacterial cell,
An organism that is found on the surface of a biofilm could be classified a a(n):
Obligate aerobe
Biological vectors
Gets into host through a bite or contact with the vectors fecal matter
Role of an epidemiologist
Getting a disease back under control when it emerges or expands from localize to epidemic
Latent disease
Have periods of no active disease follow by times of acute disease
If a conjugation plasmid incorporates into the bacterial chromosome, the cell is now labeled:
Hfr
Peroxidase
Hydroxyl radical OH: H2O2+2H+-peroxidase->2H2O
Class of organisms that would display optimal growth in the following environments: Within a rim of a boiling hot spring in Yellowstone National Park
Hyperthemophile
Which of the following is a fomite?
Hypodermic needle
You are responsible for determining the concentration of bacteria (cfus/mL) found in milk being produced by a particular dairy farm to determine if it falls within a safe limit. State the name of a method you could use to determine the concentration of bacteria. Explain your choice.
I would use the filtration method because filtration allows for the milk to be ran microbes to be ran through onto a silter then it is transferred to a nutrient agar plate to be analyzed for colony growth ad we can count to see if the colonies are within a safe limit from what was filtered from the milk.
Why is it necessary to include the following in a recipe for bacterial growth: Phosphorous
In DNA, RNA, ATP, and membrane
Why is it necessary to include the following in a recipe for bacterial growth: Nitrogen
In amino acids and proteins, most bacteria decompose proteins, some bacteria use NH4- or NO3-. Often found in soil, they are capable of fixing the nitrogen found in air and making it available for plants to use
Why is it necessary to include the following in a recipe for bacterial growth: Sulfur
In amino acids, thiamine, and biotin and most bacteria decompose proteins
Process of transcription/translation in eukaryotes
In the nucleus, a gene composed of exons and introns is transcribed to RNA by RNA polymerase, processing involves snRNPs in the nucleus to remove the intron-derived RNA and splice together the exon-derived RNA into mRNA, After further modification, the mature mRNA travels to the cytoplasm, where it directs protein synthesis
Stages involved in the development of a disease
Incubation period (initial infection and first signs/symptoms), Prodromal period (early, mild symptoms), period of illness (disease is most severe), Period of decline (signs and symptoms subside), period of convalescence (body returns to pre-diseased state)
What are transposons
Jumping genes, responsible for creating the enzyme needed for this process
Importance of virulence factors: digest membrane components
Kinases
How is LacZ used in a plasmid for gene cloning
Lactose deference
Assign the appropriate phase to the description of activity within a culture: cells are preparing for growth
Lag phase
Assign the appropriate phase to the description of activity within a culture: phase right after inoculation into a new culture
Lag phase
Phases of a microbial growth curve #1
Lag phase: cells are getting ready to divide and over all there is not a steady increase in the population numbers
Organisms found not found in a biofilm tend to be ________ to antibiotics than those found in a biofilm.
Less resistant
LD50
Lethal dose for 50% of a sample population
In order for a microbial organism to build macromolecules, it would need:
Lipids and nuclei acids
Assign the appropriate phase to the description of activity within a culture: antibiotics, such as like penicillin, has a greater affect during this phase
Log phase
Assign the appropriate phase to the description of activity within a culture: growth of cells occurring faster than the death of cells
Log phase
Phases of a microbial growth curve #2
Log phase: right after the inoculation of a fresh culture, exponential growth occurs and there is a significant increase in the overall numbers of organisms present
Direct methods of measuring cell growth: most probable number
Look at low concentrations of organisms which might be likely in food products
Class of organisms that would display optimal growth in the following environments: Inside the intestinal tract of a human being
Mesophile
Possible consequences of base substitution (point) mutations: nonsense mutation
Met-> stop
What is a biofilm?
Microbial communities that act as a biological systems in which members can protect themselves and each other and share genetic information within them
Eukaryotic microorganisms divide most cells by __________ while most prokaryotic organisms utilize _____________.
Mitosis... binary fission
Polio is transmitted by ingestion of water contaminated with feces containing polio virus. What portal of entry does polio virus use?
Mucous membranes only
Portals of entries for pathogens
Mucous membranes, skin, and parenteral route
Which organisms below would need superoxide dismutase?
Obligate aerobes only and facultative anaerobes only
Sporadic diseases
Occurs only occasionally
Parasitism
One organism benefits at the expense of the other
Compensalism
One organism benefits, and the other is unaffected
Invitation of DNA replication occurs in prokaryotes and eukaryotes at the ___________.
Origin
Endotoxins are:
Part of the Gram-negative cell wall
Catalase
Peroxide anion O2 2-: 2H2O2-catalase->2H2O+O2 (obligate aerobes, facultative anaerobes
Define bacterial growth including binary fission
Prior to division, the DNA will replicate. FTS are important in this process. FTSZ start the division of of the cell by forming a ring around the center of the cell in the space between the duplicated DNA nucleotides. FTSK and other proteins segregate the two copies of the chromosome into the developing new daughter cells as they elongate. A septum forms between the new daughter cells along the area of the FT Z ring. The cells are separate to form 2 new cells. One generation has occurred.
If a bacterium acquires a conjugation plasmid, it has the potential to:
Produce a specialized pious called a sex or mating bridge
Initiation of transcription occurs at the ______________.
Promoter
What is an exotoxin
Proteins produced and secreted by bacteria (hemolysins)
How does a biofilm form?
Random contact with a surface due to collisions and eventual attachment with either pili or fimbriae. Attachment triggers production of new gene expression, including an auto inducer known as AI-2, then quorum sensing
LD50 measures _________________________.
Rate of death in a population
What is an endotoxin
Release during bacterial multiplication and when gram negative bacteria die (septic shock)
Compare conjugation between Hfr x F-
Replication and transfer of part of the chromosome, replication and transfer of part of the chromosome, then in the recipient recombination between the Hfr chromosome fragment and the F- chromosome (F- will not get access to the entire conjugation plasmid)
Direct transmission
Requires close association between the infected and a susceptible host, physically touching
Methods an organism can exit a host
Respiratory tract, gastrointestinal tract, genitourinary tract, skin, and blood
Which of the following definitions is INCORRECT?
Secondary infection: a long-lasting illness
The antibiotic resistance gene on the pUC19 plasmid is used for:
Selection
How is complementary DNA (cDNA) used in a plasmid for gene cloning
Selective for bacteria
Nonliving reservoirs
Soil and water
A sudden outbreak of Ebola in the United States, where it is not normally found, would be known as:
Sporadic
Communicable disease
Spread through direct or indirect contact w/ an infected individual
Indirect transmission
Spreads to a host by a non living object called a fomite
Invitation of translation occurs at the ______________.
Start codon
Assign the appropriate phase to the description of activity within a culture: death of cells is occurring at the same rate as growth of the cells
Stationary phase
Phases of a microbial growth curve #3
Stationary phase: the time of equilibrium, the number of microbial deaths are balanced with the production of new cells resulting in a flatline phase of growth
Why is it necessary to include the following in a recipe for bacterial growth: Carbon
Structural organic molecules, energy source. Serve as potential oxidizing agents in anaerobic repiration
Process of DNA replication in prokaryotic cells, including leading and lagging strands
Supercoil the chromosome using specific enzymes in order to get it to fit insides, the lagging strand is synthesized, discontinuously. The leading strand is synthesized continuously from the primer by DNA polymerase
Superoxide dismutase (SOD) is responsible for the conversion of:
Superoxide anions to hydrogen peroxide and oxygen
If an organism is an obligate aerobe, you would expect it to possess:
Superoxide dismutase and catalase enzymes
Superoxide dismutase
Superoxide free radical O2-: O2-+O2-+@H+-superoxide dismutase->H2O2+O2 (obligate aerobe, facultative anaerobes, and aerotolerant anaerobes)
Real-time (qPCR)
Tell you the number of RNAs present in a specimen
The LD50 of the toxic component of chocolate is 1000mg/kg for humans but only 300mg/kg for dogs. These means that:
The chemical is more toxic to dogs than humans
the ID50 is:
The dose that will cause an infection in 50 percent of a population
All of the following are examples of entry via the parenteral route EXCEPT:
The mouth
Using what you know of transmission of infectious diseases, briefly explain, using terms to be describe transmission, how a student's professor could contract a cold from the student's child if the child never came to class with the parent.
The student's kid could have sneezed causing droplet particles to get onto the parent. When the parent went to class they closely come into contact with the teacher and pass it via indirect transmission like from borrowing a pencil or direct transmission from shaking hands.
Uses a bacteriophage
Transduction
May involve the use of chemicals or electricity
Transformation
Results in bacteria taking up DNA from the environment
Transformation
The difference between transformation and electroporation
Transformation involves the binding of foreign DNA, electroporation, an electric pulse creates pores and a temporary electric field that pulls the DNA t the more positively charged end
Vehicle transmission
Transmission by an inanimate reservoir (airborne, waterborne, foodborne)
Droplet transmission
Transmission via airborne droplets less than 1 meter
Results in movement of genetic information from one area of the genome to another
Transposon
DNA is constructed of _________.
Two strands of nucleotides running antiparallel
How can nosocomial infections be avoided
Universal precautions, standard precautions (hand washing, coughing into our elbows, PPE), and contact precautions (to limit direct contact with a patient's bodily fluids)
Regular PCR
Used to make multiple copies of a piece of DNA through the enzymatic process of DNA replication
Water, food, and air are examples of:
Vehicle transmission
Temp thermophiles/hyperthrmophiles grow
Very warm temp (usually in the Domain Archaea, a group that is known to prefer extreme environments)
Describe the control mechanisms for the lac operon
When lactose is present in the environment, will bind to the repress or and prevent it binding to the operator. This allows the RNA polymerase to produce the structural genes needed for the processing of lactose
Describe the control mechanisms for the tryptophan operon
When tryptophan becomes too high, it will bind to the repress or changing its shape. This new shape allows for binding to the operator and thus prevention of the activity of the RNA polymerase. Will go away when the tryptophan levels become lower
Pandemic diseases
Worldwide epidemic
Animal reservoirs
Zoonoses are diseases transmitted rom animals to humans
Possible consequences of base substitution (point) mutations: missense mutation
amino acid sequence: Met->Lys->Phe->Ser (instead of Gly)
Dry weight (indirect method of measuring cell growth)
bacteria are filtered, dried, and weighed; used for filamentous organisms
Microaerophiles:
cannot tolerate normal atmospheric levels of oxygen
Distinguish chemically defined and complex media
chemically defined medium: one whose exact chemical composition is known. Complex media: made up of nutrients including extracts from yeast, meat, or plants, or digest of proteins from these and other sources. the exact chemical composition varies slightly from batch to batch.
How can transposons contribute to genetic changes
contain insertion sequences for cutting and resealing DNA and allow for the carrying of genes from one region of a DNA to another
Oxygen requirements/tolerance: facultative anaerobes
flexibility in terms of their ability to generate ATP, they are able to use molecular oxygen in an aerobic respiration system or they can use alternative metabolism to generate ATP if oxygen is not available
ID50
infectious dose for 50% of a sample population Used as a measurement of the virulence of a microorganism
A disease in which the causative agent remains inactive for a time before producing symptoms is referred to as:
latent
Metabolic activity (indirect method of measuring cell growth)
measure metabolic product and assume it is in direct proportion to the number of bacteria present
Endotoxins contaminating injectable drugs could cause:
septic shock symptoms