Micro Final Exam
What usually terminates the process of translation?
Presence of a stop codon on mRNA
When studying microbes, why is it important to separate mixed communities into individual pure cultures of the different species?
So we can understand the biochemical characteristics of one species without confusing it with another species.
Which of the following could be another "good" reason for the meat still rotting?
The "vital force" required for life could still penetrate the cloth and cause the meat to spontaneously change.
Which of the statements about catabolism and anabolism is TRUE?
The energy gathered during catabolism is used during anabolism.
Which of the following is an example of activation energy?
The energy of a small flame used to light the natural gas of a Bunsen burner.
In order for cells to obtain energy, they remove electrons from an energy source and ultimately donate them to the terminal electron acceptor. What does this tell us about the electron affinity of the energy source and the terminal electron acceptor? Multiple choice question.
The energy source has a lower affinity for electrons, and the terminal electron acceptor has a higher affinity for electrons.
Which of the following statements about newly emerging or reemerging diseases is FALSE?
They are all caused by drug-resistant pathogens.
Which of the following is FALSE about transposons?
They are capable of moving independently from one cell to another cell.
Select the statement that is TRUE regarding viroids.
They are naked (lacking a protein shell) pieces of RNA.
Select the FALSE statement regarding bacteria.
They are never photosynthetic.
Which if the following is TRUE regarding viruses?
They are obligate intracellular parasites.
Which is TRUE about prions?
They are only composed of protein
Which is (are) true of coenzymes?
They are organic molecules. They transfer atoms from one molecule to another. They may bind to a number of different enzymes. They are synthesized from vitamins.
Why does M. tuberculosis manipulate the macrophage that engulfs it?
To avoid destruction by the macrophage
Please select the INCORRECT statement regarding mutation.
A missense mutation is also called a synonymous mutation, meaning no change in the amino acid encoded.
frameshift mutation
A mutation resulting from an insertion or deletion of bases that causes a change in the reading frame of the mRNA.
silent mutation
A mutation that changes a codon into a different codon, but both codons specify the same amino acid; this causes no change in the resulting polypeptide.
nonsense mutation
A mutation that changes a codon that specifies an amino acid to a stop codon, resulting in premature termination of polypeptide synthesis.
missense mutation
A mutation that results in changing a codon such that a different amino acid is specified.
The material responsible for transformation was shown to be DNA by
Avery, MacLeod, and McCarty.
glucose salts agar
Chemically defined medium. Used in laboratory experiments to study nutritional requirements of bacteria. Not selective or differential.
cell counting instruments
Coulter counters and flow cytometers count total cells in dilute solutions. Flow cytometers can also be used to count organisms to which fluorescent dyes or tags have been attached.
Formation of large Ab-Ag complexes as a result of the Ab binding two separate antigens
Cross-linking
Heart muscle is damaged after a heart attack (MI) because blood flow to the heart is stopped. A researcher injected cyanobacteria into the damaged hearts of test animals that has been given MIs. The animals' conditions improved after the procedure, but not significantly. The researcher repeated the experiment, this time illuminating the cyanobacteria with high intensity light after injecting the cells into the damaged hearts. Now the animals did much better, recovering well from their heart attacks. Which of the following explains this outcome?
Cyanobacteria produce oxygen by photosynthesis. Illuminating the cells increases amount of O2 released that is then used by heart cells for aerobic respiration.
Which of the following correctly describe cytochromes found in an electron transport chain?
Cytochromes are proteins that contain heme, a molecule that holds an iron atom in its center. Several different cytochromes exist.
Prions A. contain only nucleic acid without a protein coat. B. replicate like HIV. C. integrate their nucleic acid into the host genome. D. cause diseases of humans. E. cause diseases of plants.
D. cause diseases of humans
Which tasks must a bacterial cell accomplish in order to multiply?
DNA duplication, RNA synthesis, protein synthesis
Please select all of the differences between DNA and RNA to test your understanding of these nucleic acids.
DNA is double-stranded, RNA is single-stranded. Correct DNA nucleotides contain deoxyribose whereas RNA nucleotides contain ribose. There are multiple types of RNA with different functions whereas there is only one type of DNA.
Which of the following shows the direction genetic information flows?
DNA → RNA → protein
Why were people still so unwilling to dismiss spontaneous generation even after Father Spallanzani's experiment?
For about 1,900 years, spontaneous generation was shown to be "true" by repeated observations.Correct
Why does Aggregibacter actinomycetemcomitans synthesize leukotoxin A?
For self-defense—the toxin protects the bacterium against phagocytes such as neutrophils.
Which of the following contribute to antibody diversity?
Gene rearrangement, imprecise joining AND combinatorial associations
Transduction resulting from a packaging error.
Generalized transduction.
What are the effects of increasing the pressure of water in an autoclave?
Increases the temperature at which steam forms Increases the boiling point of water
Please select the statements that are true of inducible operons to test your understanding of the differences between inducible and repressible operons.
Inducible operons often contain genes for enzymes that function in catabolic processes. Inducible operons will be "turned on" in the presence of the substrate and "turned off" in its absence. The lac operon is an example of an inducible operon.
acute infection
Infection in which a virus multiplies rapidly and spreads in the host.
When E. coli is placed in a medium containing both glucose and lactose, why does cell growth stop temporarily when the glucose is used up?
Once glucose is depleted, the cell must use the lactose; before it can do this, it must express the lac operon and synthesize the enzymes needed to use lactose, which takes time.
Select the statement that does NOT apply to a fluorescence microscope.
It uses electrons to produce an image of the specimen.
In respiring bacteria, how does ATP synthase generate ATP?
It uses the energy released from allowing protons to flow back into the cell to add a phosphate group to ADP.
Two bacterial genes are transduced simultaneously. What does this suggest about their proximity to each other within the original host genome?
It's highly likely that the two genes are located next to each other in the host cell chromosome. Since transduction results from a packaging error or an excision error that occurs during the infection cycle of the bacteriophage, the genes must lie close to each other to be transduced into a new cell simultaneously.
Why is it important to completely remove all traces of ethylene oxide from items used to grow bacteria?
Its persistent effect will not allow the microbes to grow.
On one of the strands of bacterial DNA, the new complementary strand is synthesized discontinuously in small pieces of DNA called ______.
Okazaki fragments
In prokaryotic DNA replication, which of the following is FALSE?
On one parent strand, the polymerase synthesizes DNA in the 5' to 3' direction, while on the other it synthesizes DNA in the 3' to 5' direction.
Gene regulation may entail: turning on genes only when needed.Incorrect turning off genes when not needed. turning on or off entire groups of genes. All of the answer choices are correct.Correct None of the answer choices is correct.
all of the choices are correct
Which of the following occur(s) in both prokaryotes as well as eukaryotes? DNA replication All of the choices are correct. Translation Transcription None of the choices are correct.
all of the choices are correct
A sterile item is free of
all viable microbes, endospores, AND viruses
The two strands of the DNA molecule are ______.
antiparallel
Please choose the statement that best describes the role of viral surface proteins or spikes
Viral spikes provide means of attachment to host cell surface
Please choose the statement that best describes the role of viral surface proteins or spikes.
Viral spikes provide means of attachment to host cell surface.
Generalized transduction occurs when
a bacteriophage packages a piece of bacterial DNA during replication
Negative staining is commonly used to determine if bacterial cells have
a capsule
Hfr refers to
a cell in which the F plasmid has been integrated into the cell chromosome.
RNA
a chain of nucleotides, each made of a sugar, a phosphate group, and a nitrogen-containing base
Endospores are
a dormant cell type
During maturation or formation of phage particles
a few phage heads may surround fragments of host bacterial DNA
During maturation or formation of phage particles,
a few phage heads may surround fragments of host bacterial DNA.Not attempted
A single species of bacteria grows best at
a modest range around an optimum temperature.
promoter
a nucleotide sequence on a DNA molecule to which an RNA polymerase molecule binds to start transcription
Oxygen serves as the terminal electron acceptor in
aerobic respiration
The light-independent reactions of photosynthesis occur _______ the light-dependent reactions, and function to _______.
after; synthesize organic compounds from CO2
The solidifying agent used most successfully in bacterial nutrient media is
agar
Which of the following chemical classes destroy microorganisms by forming chemical bonds that cross-link and inactivate proteins and nucleic acids?
aldehydes
The largest group of chemical mutagens consists of
alkylating agents.
The advantageous genes that can be transferred by transduction are genes for: sugar fermentation. toxin production. drug resistance. All of the answer choices are correct. None of the answer choices is correct
all correct
As part of cellular respiration, a membrane-bound enzyme called ATP ________ uses energy from a proton-motive force to add a phosphate group to ADP.
synthase
Which molecule carries an anticodon?
tRNA
Which is not involved in adaptive immunity?
tear flow
Flagella are typically difficult to see using a light microscope because
too thin to be seen, require specific staining
Metagenomics is the analysis of
total microbial genomes in an environment.
The type of food-borne infection known as an intoxication is caused by
toxins produced by microbes as they grow in the food
Degradation of fats as an energy source involves all of the following except
transamination
which of the following statements about gene expression is false?
translation begins at a site called a promoter
Segments of DNA capable of moving from one area in the DNA to another are called
transposons.
Both enveloped and non-enveloped (naked) viruses can enter a cell by endocytosis.
true
If you know the sequence of nucleotides in mRNA, you can deduce the DNA sequence it was transcribed from.
true
Improper base-pairing during DNA replication causes a pause in chain elongation.
true
Prokaryotes lack membrane-enclosed organelles.
true
Replication, transcription and translation take place in the bacterial cytoplasm.
true
Some bacteria can congregate together to form multicellular associations.
true
Sometimes a piece of bacterial DNA near the specific site of insertion stays attached to the phage DNA, and a piece of phage DNA remains behind.
true
The donor cell DNA is integrated into the recipient cell's DNA by homologous recombination.
true
The lambda phage DNA always integrates into the host DNA in the same specific site.
true
The sequence of DNA bases ultimately determines the sequence of amino acids in a polypeptide.
true
True or false: With respect to the location of the electron transport chain, the inner membrane of mitochondria is analogous to the cytoplasmic membrane of bacterial cells.
true
Unlike DNA, RNA is usually single-stranded.
true
Gene regulation may entail
turning on genes only when needed.Incorrect turning off genes when not needed. turning on or off entire groups of genes. None of the answer choices is correct.
Choosing the correct antimicrobial procedure depends on many factors including ______.
type and number of microbes composition of item environmental conditions
transfer rna (tRNA)
type of RNA molecule involved in interpreting the genetic code; each tRNA molecule carries a specific amino acid
tRNA
type of RNA molecule present in ribosomes
ribosomal rna (rRNA)
type of RNA that makes up the major part of ribosomes
mRNA
type of rna molecule that contains the genetic information decoded during translation
Some prokaryotes can live in multicellular associations. An example of this, which has medical importance, is ______.
bioflilms
Although the pentose phosphate pathway is used by cells to break down glucose, it is particularly important because of its contribution to ______.
biosynthesis
In humans, the stem cells from which all blood cells arise are found in the
bone marrow
Which of the following is a primary lymphoid organ?
bone marrow
When the defective phage enters a new bacterial cell
both phage DNA and bacterial DNA integrate into the chromosome of the new cell host.
Facilitated diffusion and active transport
both transport molecules into or out of a cell.
After entry of the bacteriophage into the host cell, a phage enzyme
breaks the host DNA into fragments
A plasmid that can replicate in E. coli and Pseudomonas is most likely:
broad host range plasmid
temperate phages can do all of the following except
bud from their host cells
How do aqueous solutions of alcohol usually affect microbes?
by damaging lipid membranes by denaturing proteins
Mercury in mercurochrome inhibits growth
by oxidizing the sulfhydryl groups in cysteine AND by changing the shape of proteins.
Immune complexes activate complement proteins, leading to inflammation and production of MACs
complement system activation
sigma factor
component of rna polymerase that recognizes a promoter. A cell can have different types of sigma factors that recognize different promoters, allowing the cell to transcribe specialized sets of genes as needed.
the donor cell typically survives which DNA-transfer process
conjugation
Horizontal gene transfer can occur via
conjugation.
The membranes of eukaryotes and mycoplasma
contain sterols for strength.
The cell wall of Gram-positive bacteria
contains a thick layer of peptidoglycan.
UV light exposure forms
covalent bonds between adjacent thymine nucleobases on the same strand of DNA
UV light and other non-ionizing radiation damage DNA molecules by
creating thymine dimers between adjacent thymine nucleobases in the DNA chain.
A surgical scalpel is rated as a ______ instrument because it penetrates skin and mucous membranes and therefore must be sterile. Multiple choice question.
critical
Medical instruments are classified into three categories according to their risk for transmitting pathogens. These are:
critical, semicritical, noncritical
Examples of electron carriers are proteins that contain heme, a molecule that holds an iron in its center. These are called
cyotchromes
Complement factors C5b+C6+C7+C8 make up a membrane attack complex that results in
cytolysis
The changes that occur in virally infected cells are characteristic for a particular virus and are referred to as the
cytopathic effect.
In prokaryotes, the electron transport chain is located in the ________ membrane, whereas in eukaryotic cells it is in the ______ membrane of mitochondria.
cytoplasmic; inner
In the growth curve of a bacteria population, the bacteria are rapidly increasing in number in the
exponential (log) phase.
Secondary lymphoid organs
facilitate interactions between cells.
After conjugation of an Hfr cell and an F- cell, the entire genome of the Hfr cell is usually transferred to the recipient cell.
false
Bacteria are only visible when using an electron microscope.
false
Bacteria that look alike are probably members of the same species.
false
Complement factors are named in the order in which they function.
false
Generalized transduction involves the transfer of phage genes from one bacterial cell to another.
false
Generalized transduction is so called because specific bacterial genes are transferred during this process.
false
In general, bacterial cells are larger than human cells.
false
Once a phage becomes lysogenic, it will remain lysogenic and never be lytic again
false
T-even phages can replicate independently of a host cell.
false
The purpose of RNA synthesis is to provide a new copy of DNA as the original strand deteriorates over time.
false
True or false: The Calvin cycle is a two-step linear pathway that photosynthetic organisms use to fix carbon dioxide
false
True or false: There is a standard antimicrobial procedure available from the Centers for Disease Control and Prevention (CDC) that can be used for all different microorganisms under any condition. True false question.
false
Microorganisms that have complicated nutritional requirements are
fastidious
Glucose catabolism encompasses two key processes: (1) oxidizing glucose molecules to generate ATP, reducing power, and precursor metabolites; and (2) transferring the electrons carried by NADH and FADH2 to the terminal electron acceptor. The second process, transfer of electrons, is accomplished as part of which of the following?
fermentation cellular respiration
One of the strongest indications of infectious disease is
fever
Agar replaced gelatin as the gelling (solidifying) agent for media because
fewer bacteria can break down agar compared with gelatin.
There are ______ class(es) of antibody.
five
The three main types of electron carriers in a typical electron transport chain are
flavoproteins, quinones, cytochromes
A staining technique that uses immunofluorescent dyes or antibodies will typically use which of the following types of microscopes?
flourescent microscope
Production of extracellular polymeric substances (EPS) enables bacteria to
form biofilms.
Formalin is 37% aqueous solution of ________ that is used as a potent chemical fixative and microbicide.
formaldehyde
_______ is used to kill bacteria and inactivate viruses in vaccines. It can also preserve biological specimens.
formaldehyde
The electron transport chain of mitochondria has ______ different protein complexes.
four
primer
fragment of nucleic acid to which DNA polymerase can add nucleotides
The enveloped viruses typically obtain their envelope
from the host cytoplasmic membrane as they exit the host.
In conjugation, transformation, or transduction, the recipient bacteria is most likely to accept donor DNA
from the same species of bacteria.
gene
functional unit that controls inherited trait expression that is passed on from one generation to another generation
Although generally less reliable than heat, germicidal chemicals are especially useful for treating ______. Multiple select question.
heat-sensitive items large surfaces
Early in the process of DNA replication, the enzyme ______ separates the two strands.
helicase
The best-known examples of viruses that cause latent infections are
herpes AND chickenpox.
what is used to decrease the number of microbes in food while maintaining the color and flavor.
high pressure processing (HPP)
All of the following are characteristics of bleach, a solution of sodium hypochlorite, EXCEPT
it is only effective against a limited range of microorganisms
Hand washing with plain soap is very effective in controlling spread of microorganisms because
it is very effective at the mechanical removal of microorganisms.
When a bacterium is grown on glucose only,
it must synthesize all the amino acids it needs
The capsule
may be used for protection AND may be used to help the bacteria adhere to surfaces.
The term "segmented" refers to viruses that
may contain several pieces of RNA.
Assembly of the T4 phage
may involve some self-assembly AND may involve the use of scaffolds.
Anoxygenic photosynthetic bacteria
may obtain electrons from H2S.
Chemical germicides
may react irreversibly with proteins/enzymes. may react with cytoplasmic membranes or viral envelopes. may be disinfecting or even sterilizing. are sensitive to dilution factor, time of contact, and temperature of use.
The series of sequential chemical reactions in a cell that converts a starting compound to an end product is called a _____ pathway
metabolic
The lag phase of the bacterial growth curve is marked by
metabolically active cells.
Outside of living cells, viruses are
metabolically inert.
The general term used to describe the anabolic and catabolic reactions in a cell is
metabolism
The sum total of all chemical reactions in a cell is called
metabolism
DNA is protected from restriction enzymes by being
methylated.
Which of the following cytoskeletal elements are found within the eukaryotic flagella?
microtubules
The enzymes of the tricarboxylic acid cycle are found in the ______ matrix in eukaryotes and in the _____ in prokaryotes.
mitochondrial; cytoplasm
Household bleach applied at 55C is ________ effective in killing bacteria than if it were applied at 50
more
Chlorhexidine solutions are commonly used for ______.
mouthwashes antisepsis of skin and skin wound care
The ribosomes
move along the mRNA in a 5'-3' direction AND provide a platform that brings the amino acids into a favorable position for joining.
Chemotaxis refers to
movement in response to a chemical
The smallest virus is approximately 10 ______ in diameter.
nanometers
Prions affect the
nervous system
Antibodies fill the surface receptors on microbe to prevent attachment to the host
neutralization
The first kind of leukocyte lured to the site of inflammation is the
neutrophil
A medical technician examines a Gram stain of purulent discharge (pus) from a patient with an active infection. Which predominant host cell type will the technician most likely see?
neutrophils
Which of the following are considered the major elements that primarily make up components of cells in microorganisms and all living things?
nitrogen phosphorous sulfur carbon
Prior to using microscopes, do you think most people knew of biological activities such as flies laying eggs?
no
If Gene X codes for an F pilus and transposition occurs, then the bacterium containing the plasmid would
no longer be able to conjugate.
Alcohols are not reliably effective at destroying
non-enveloped viruses AND endospores.
Which four of the following microbial groups are the most resistant to chemical control methods?
nonenveloped viruses bacterial endospores Mycobacterium species protozoan cysts and oocysts
okazaki fragment
nucleic acid fragment produced during discontinuous synthesis of the lagging strand of DNA
terminator
nucleotide sequence at which RNA synthesis stops; the RNA polymerase falls off the DNA template and releases the newly synthesized RNA
RNA is a chain of ______.
nucleotides
Select which of the following are applications of fluorescent staining.
observing a subset of cells within a larger population identifying bacteria by tagging unique surface proteins
Exergonic reactions
occur when there is more free energy in the reactants than the products.Correct
Using phages to treat a bacterial infection is an interesting idea because
of the increasing problem of antibiotic resistance in pathogens.
The variable region of an antibody occurs
on all 4 chains.
A recombinant organism is
one that that contains genes from another organism.
In the process of specialized transduction
only a few specific genes from one bacterial cell are transferred to the second bacterial cell by a phage.
In specialized transduction
only bacterial genes near the site of integration of the phage DNA can be transduced.
Bacteriophages adsorb or attach
only to members of the same bacterial species
The DNA site to which the repressor protein binds is the
operator
Coordinated sets of genes that are regulated as a single unit are referred to as ______.
operons
The specific point on the DNA molecule where replication begins is the
origin of replication
Coating of microbe with antibody to enhance phagocytosis
osponization
The TCA cycle completes the ______ of glucose.
oxidation
Halogens are highly reactive _______ agents that _______.
oxidizing; cause damage to proteins
Used as an alternative to chlorine for disinfecting water, ______ is a strong but unstable oxidizing agent that must be generated on-site, usually be passing air or O2 between two electrodes.
ozone
Microbial death rates may be affected by
pH. temperature. the presence of organics. growth in a biofilm.
Bacteria have been used to help produce or modify all of the following food products EXCEPT
peanuts
To isolate penicillin-resistant mutants, the scientist must inoculate the parent population on plates containing ______; this approach is ______ selection.
penicillin; direct
The central metabolic pathway that generates reducing power in the form of NADPH is the ____ ______ pathway.
pentose phosphate
Proteins are hydrolyzed by proteases, enzymes that break the _____ bonds between amino acid subunits.
peptide
The bond connecting amino acids is a ______ bond.
peptide
nutrient broth (complex medium)
peptone, beef extract, water
When selecting an appropriate chemical disinfectant, it is important to realize that the death rate is significantly influenced by
ph temperature
After host cell DNA is broken down by a viral enzyme
phage DNA is replicated and phage coat proteins are produced
Colonies of the bacterium Serratia marcescens are red when incubated at 22°C but white when incubated at 37°C. This is an example of
phenotypic change.
The three basic parts of a DNA nucleotide are
phosphate, deoxyribose sugar, nitrogenous base
Bacteria that can absorb light energy and convert it into ATP are commonly called
phototrophs
The chemical ortho-_______ provides an alternative to glutaraldehyde because it is less irritating on the eyes. However, it does stain skin proteins gray.
phthalaldehyde
If cells were exposed to UV light, the highest frequency of mutations would be obtained if the cells were immediately
placed in the dark
Spongiform encephalopathy occurs in all of the following EXCEPT
plants
Determining viral titers of both phage and animal viruses frequently involves
plaque formation
Antibodies are produced by
plasma cells
A difference between plasmids and fragments of DNA that have been transferred between cells is
plasmids can replicate independently.
A difference between transferring plasmids and DNA fragments between bacterial cells is
plasmids can replicate independently.
A high-solute environment damages microbial cells by causing ______. Multiple choice question.
plasmolysis
After a deamination reaction removes the amino group from amino acids, the remaining carbon skeletons are converted into the appropriate ______ metabolites for entry into central metabolic pathways.
precursor
In addition to yielding energy, catabolic pathways generate carbon intermediates that can be used in anabolic pathways for the biosynthesis of macromolecules. These carbon skeletons are called
precursor metabolites
A limiting factor for viral infection of animals cells is
presence of specific receptor molecules on the host cell.
Silver sulfadiazine, a combination of silver and a sulfa drug, is used to
prevent infection of second- and third-degree burns.
If you find that a particular plasmid has an R factor, the bacteria that has it will be
resistant to certain antibiotics.
The transcription terminator
results in a hairpin loop structure in RNA, AND results in the polymerase falling off the DNA template.
Protein synthesis occurs on the ______.
ribosomes
Transposons are
segments of DNA.
A medium that inhibits the growth of organisms other than the one being sought is called a(n)
selective medium.
During apoptosis, a cell will
self-destruct without causing an inflammatory response.
The resolving power of a microscope is described as the ability of the microscope to
separate clearly two objects that are very close together.
Which term is used to describe the region of a protein that directs the secretion machinery to move the protein across a cytoplasmic membrane?
signal sequence
What structure is indicated by: 10A, 15T, 3G, 7C?
single stranded DNA
During conjugation, the donor chromosome is transferred as
single-stranded DNA.
classification of viruses is based on all of the following except
size of the virus
Most enzymes function best at
slightly above pH 7 and low salt concentrations.
Transduction resulting from an error in excision of a prophage.
specialized transduction
The F pilus binds to
specific receptors on the cell wall of the recipient.
In the region of budding, the cytoplasmic membrane acquires
spike proteins AND matrix proteins
Below is an outline of Louis Pasteur's swan-neck flask experiment. What can you conclude from his results?
spontaneous generation is incorrect. only life can beget life. Microbes can be found in the air.
The term used to describe a cluster of spherical bacteria is ______.
staphylococci
In which organism were phagocytes first reported?
starfish larvae
The process of destroying or removing all microbes through physical or chemical processes is ______.
steralization
A common application of dry heat in the microbiology laboratory is to
sterilize the inoculating loop.
(+) strand of dna
strand of DNA complementary to the one that serves as the template for RNA synthesis; the nucleotide sequence of the RNA molecule is the same as this strand, except it has uracil rather than thymine
(-) strand of dna
strand of DNA that serves as the template for RNA synthesis; the resulting RNA molecule is complementary to this strand
ribosome
structure that facilitates the joining of amino acids during translation; composed of ribosomal RNA and protein
Enzymes function as biological catalysts, accelerating the conversion of one substance, the ______, into another, the ________
substrate; product
Examples of advantageous genes that can be transferred by transduction are genes for
sugar fermentation. toxin production. drug resistance. only drug resistance and toxin production.
Organisms may derive energy from
sunlight AND metabolizing chemical compounds.
The enzymes that deal with toxic oxygen-containing molecules is/are
superoxide dismutase AND catalase.
F+ cells
have a plasmid and are donors in conjugation
The time from absorption to release for T-even phage is about
30 minutes.
The surface receptors on B and T cells both
have variable and constant regions.
Which of the steps shown is unique to the endospore stain?
heat
Which of the following is used to classify viruses? i. Nucleic acid ii. Shape iii. Size iv. Host range v. Biochemical tests
(i), (ii), (iii), and (iv)
Which of the following are examples of biofilms?
- Dental plaque - Scum accumulating in toilet bowls - Slipperiness on rocks in stream beds
"Clonal selection" and "clonal expansion"
- imply that each individual lymphocyte produces a single antibody - describe how a single lymphocyte proliferates in a population of effector cells - depend on an antibody recognizing a specific epitope - explain how an antigen stimulates the production of matching antibodies
all phages must be able to
- inject their nucleic acid into a host cell -have their nucleic acid replicate in the host cell
acute infections of animals
-are the result of productive infection -generally lead to long-lasting immunity
detecting cell products
-used to detect growth not routine for quantitation. pH indicator can be used to detect acid production. gases can be trapped in an inverted tube in the broth. more sensitive method uses a fluorescent sensor that detects slight dec in pH that accompanies carbon dioxide production
Identify which of the following are eukaryotes. 1. Algae 2. Bacteria 3. Viruses 4. Prions 5. Protozoa
1,5
Which of the following are true statements about what happens to glucose inside a cell?
1. Glucose can be used in catabolism to yield energy, or the precursor metabolites generated from its breakdown can be used in anabolism. 2. Some glucose might enter glycolysis, only to be siphoned off as a precursor metabolite for biosynthesis. 3. Some glucose might be oxidized to CO2, generating the maximum amount of ATP.
You are studying a cell with 20% of its DNA composed of T nucleotides. What percentage of the nucleotides are C?
30
3 key central metabolic pathways and beneficial products
1.glycolysis, 2.pentose phosphate pathway, 3.TCA cycle Benefits: ATP, precursor metabolites, reducing power
How long after initiation of a primary response do significant amounts of antibody appear in the blood?
10-14 days
Typical conditions used for sterilization are
121°C at 15 psi for 15 minutes.
There are ______ major families of RNA containing viruses that infect vertebrates.
13
George Beadle and Edward Tatum
1941, showed precise function of genes; revealed that genes direct the production of enzymes
Arrange the following events in clonal selection in the correct order: 1. Helper T cells are activated. 2. Macrophages ingest antigen. 3. B cells differentiate into plasma cells and memory cells.
2,1,3
Proteins are composed of various combinations of usually how many different amino acids?
20
In the case of T-even phages, the burst size is about
200 per host cell
A thermophile is grown at two different temperatures. Which results would be expected for this organism?
220 minutes at 42°C; 20 minutes at 65°C
A pure culture in exponential growth phase has a bacterial concentration of 6.4 x 108 cells/ml. If the bacterium has a generation time of 1 h, how long ago was the cell concentration 8.0 x 107 cells/ml?
3 h
DNA polymerases use their ______ activity to remove a mismatched base pair.
3' -> 5' exonuclease
Arrange the following in the proper order in which they first appear in the alternative pathway of complement activation. 1. Factor B 2. Factor D 3. C3
3,1,2
Arrange the following sets of names from MOST closely related to LEAST closely related: 1. Bacillus anthracis - Bacillus thuringiensis 2. Hipuris vulgaris - Proteus vulgaris 3. E. coli HB101 - E. coli DH5α
3,1,2
Please select the correct sequence for the steps of phagocytosis: 1. Conditions in the phagosome change, increasing its antimicrobial activities. 2. The phagocytic cell binds microbial invaders and engulfs them, internalizing them in a phagosome. 3. Phagocytic cells are recruited to the site of an injury by chemoattractants. 4. Within the phagolysosome, various factors work together to destroy an engulfed invader. 5. The phagosome fuses with enzyme-filled lysosomes, forming a phagolysosome.
3,2,1,5,4
A urine sample with more than 100,000 organisms is considered indicative of infection. A urine sample containing 5,000 bacteria, with a generation time of 30 minutes, sits for 3 hours before finally being assayed. How many bacteria will then be present within the sample?
320,000
The optimal temperature for most human pathogens might be expected to range from
35-40 celcius
If the theoretical maximum ATP yield in prokaryotes from oxidative phosphorylation is 34 ATP for a single glucose molecule, what is the total ATP gain when substrate-level phosphorylation is included?
38 ATP
Chlorine-releasing compounds such as sodium hypochlorite (bleach is a 5.25% solution) are used for all of the following EXCEPT 1. swimming pool treatments 2. food equipment sanitation 3. household cleaning 4. wound treatment and skin cleansing 5. sewage and waste water disinfection
4. Wound treatment/skin cleansing
Aqueous solutions of alcohol at a concentration of ______ are more effective than 100% alcohol.
60-80%
There are ______ major families of DNA-containing viruses that infect vertebrates.
7
ribosome (prokaryotic)
70s: 50s and 30s subunits
If you wanted to increase your chances of isolating a member of the Archaea (and no organisms from another domain), which sample site would you choose?
A 95oC hot spring in Yellowstone National Park.
People who have compromised first-line defenses are susceptible to opportunistic pathogens. Which situation would be an example of a compromised first-line defense?
A burn patient who has lost extensive areas of the skin.
Which of the following statements regarding bacterial genetics is/are TRUE?
A change in genotype can change the phenotype. An auxotroph has a different genotype than a prototroph. An auxotroph has a different phenotype than a prototroph.
DNA
A double-stranded, helical nucleic acid molecule capable of replicating and determining the inherited structure of a cell's proteins.
Immunity to superinfection (infection of a cell at a later time with a second, identical bacteriophage) is a consequence of lysogeny. Why does this occur?
A repressor produced by the first virus will actively suppress the lytic cycle of the second virus.
Which of the following is required to maintain a lysogenic state?
A repressor protein
Which of the following are reasons an organism might use fermentation?
A suitable inorganic terminal electron acceptor is not available. They lack an electron transport chain.
If the codon GGU is positioned in the A site of the ribosome, which of the following will occur?
A tRNA with the anticodon CCA will deliver its amino acid to the site
Which pairing is incorrect?
A:G
All of the following are essential for an electron transport chain to function EXCEPT ______.
ATP
The main energy currency of cells is the molecule called
ATP
Which enzyme drives ATP synthesis in respiration?
ATP synthase
Which of the following is required for prion replication?
Abnormal Prion Protein
alkylating agents
Add CH3 and others to nucelobases
If an organism lost the ability to make primase, what would it be unable to do?
Add a short sequence of complementary RNA to the existing DNA strand
Which change in a gene's DNA sequence would have the least effect on the eventual amino acid sequence produced from it?
Addition or deletion of three consecutive nucleotides
You use the streak-plate method to obtain a pure culture and observe individual colonies following incubation. Consider a single bacterial colony. All of the following statements about the colony are true EXCEPT:
All cells in the colony are expressing the same set of genes and are performing the same metabolic functions.
To reduce or eliminate disease-/spoilage-causing organisms, food is often subjected to
All of the answer choices are correct.
A quick microbiological test for potential carcinogens was developed by
Ames
which of the following statements is false
An example of a two-component regulatory system is the lactose operon, which is controlled by a repressor and an activator
IgG molecules attach to a cell targeting it for attack by a NK cell
Antibody-dependent cellular cytotoxicity (ADCC)
Identify the role(s) of natural killer cells.
Antibody-dependent cellular cytotoxicity AND negative selection of lymphocytes that recognize normal "self" molecules AND regulation and direction of certain immune responses.
Which of the following about the Golden Age of Medical Microbiology is FALSE?
It started with the development of the first microscopes.
Antibodies are made by
B cells and plasma cells
In the scientific names below, which designates the STRAIN? Escherichia coli B12 Bacillus subtilis E. coli Escherichia B. subtilis
B12
Which of the following genes are likely to be found on a plasmid rather than on the bacterial chromosome?
BT toxin gene Chloramphenicol-resistance gene. Oil degradation enzyme genes
The prokaryotic domain includes
Bacteria and Archaea
Please select the TRUE statement regarding preservation of perishable products
Bacterial resistance to some of the chemicals included to perishable products has been reported.
Chemolithotrophs near hydrothermal vents support a variety of life forms. Why is this analogous to photosynthetic microbes supporting life forms closer to the surface of the planet?
Because all life forms need some energy source, electron source, and carbon source. Chemolithotrophs fix inorganic carbon and, if consumed by other microbes, could serve as sources for all three requirements for life. This is very similar to the role that photosynthetic microbes play in the top levels of the oceans/lakes.
measuring biomass
Biomass can be correlated to cell number
Which of the following involves genetically modifying bacteria to produce compounds useful to humans?
Biotechnology
Which of the following use moist heat to destroy microbes?
Boiling Pasteurization Pressurized steam
Select the ways that plant viruses can infect plants.
By contaminated insects feeding on plant cells and disrupting the cell wall. By soil that was previously used to grow infected plants. Through grafting infected plant tissue onto healthy tissue.
With respect to their synthesis, how are amino acids typically grouped?
By structurally related families that share common biosynthesis pathways
Considering the general equation that describes photosynthesis, the rate of the process would be most influenced by the availability of _______ in the atmosphere.
CO2
A physician is attempting new therapies for HIV patients who are suffering from an impaired immune response. He decides to try using a recombinant form of colony-stimulating factor cytokine (CSF). Why
CSF will help to stimulate the production of new lymphocytes, the very cells that are affected by HIV. This may help to keep the patients' immune responses "normal" for a period of time.
Please select the MISMATCHED pair.
Capsules and slime layers - phospholipids
Select the FALSE statement regarding capsules.
Capsules take up stain well.
Please select the TRUE statement regarding metabolic processes.
Catabolic processes harvest the energy released during breakdown of compounds to synthesize ATP.
Preventing phage attachment.
Changing or covering up the molecules on the surface of the bacterium to which the phage particle binds.
Which of the following descriptions fits a chronic viral infection?
Characterized by continuous production of low levels of viral particles, potentially even in the absence of active symptoms of disease. The organism is usually still highly infectious during this time.
start codon
Codon at which translation is initiated; it is typically the first AUG after a ribosome-binding site.
stop codon
Codon that terminates translation, signaling the end of the protein; there are three stop codons.
nutrient agar
Complex medium used for routine laboratory work. Supports the growth of a variety of nonfastidious bacteria. Not selective or differential.
blood agar
Complex medium used routinely in clinical labs. Differential because colonies of hemolytic organisms are surrounded by a zone of red blood cell clearing. Not selective.
chocolate agar
Complex medium used to culture fastidious bacteria, particularly those found in clinical specimens. Not selective or differential.
MacConkey Agar
Complex medium used to isolate Gram-negative rods that typically reside in the intestine. Selective because bile salts and dyes inhibit Gram-positive organisms and Gram-negative cocci. Differential because the pH indicator turns pink-red when the sugar in the medium, lactose, is fermented.
Thayer-Martin agar
Complex medium used to isolate Neisseria species, which are fastidious. Selective because it contains antibiotics that inhibit most organisms except Neisseria species. Not differential.
Which step/component of phagocytosis is/are affected by the genetic defect causing CGD?
D
Which may result in Gram-positive bacteria appearing to be Gram-negative?
Decolorizing too long AND using old cultures.
Which amino acid is found only in the cell walls of bacteria?
Diaminopimelic acid
Your instructor wants you to bring in an example of a biofilm to your lab. Which choice is the best selection for bringing in an intact biofilm for further study?
Disconnecting and bringing in the old, mildewed showerhead from your bathroom.
High-level disinfection
Disinfectants that destroy all viruses and vegetative organisms but not endospores. Used for semi-critical instruments (endoscopes)
Which of the following statements about normal microbiota is FALSE?
Disruption of the normal microbiota has little effect on the host.
Which are essentially equivalent treatments?
Dry 200°C heat for 1.5 hours; wet 121°C heat for 15 minutes
Which of the following best describes vertical gene transfer?
Duplicating the entire genome and passing a copy to a daughter cell
Which of the following is an example of phase variation?
E. coli producing pili for attachment to epithelial cells.
activation energy
Energy needed to get a reaction started
dna gyrase
Enzyme that temporarily breaks the strands of DNA, relieving the tension caused by unwinding the two strands of the DNA helix
helicases
Enzymes that unwind the DNA helix at the replication fork.
most probable number
Estimates the likely concentration; it does not provide a precise count.
______ oxide is an extremely useful gaseous sterilizing agent that destroys all microbes and is often used to sterilize fabric, equipment, and implantable devices.
Ethylene
Select the TRUE statement(s) regarding eukaryotes.
Eukaryotes have a more complex internal structure than archaea or bacteria AND have a membrane around the DNA.
What are two ways that phage can replicate without directly lysing their host cell?
Extrusion and lysogeny
The TCA cycle produces
FADH2, NADH, and precursor metabolites.
In order to form lipids, how are fatty acids and glycerol synthesized?
Fatty acid chains are assembled from 2-carbon acetyl groups from the transition step; the precursor to glycerol comes from glycolysis.
Check the TRUE statements about fever induction and outcomes.
Fever is induced by cytokines called pyrogens. Fever inhibits bacteria from growing by inhibiting their metabolism. Fever results when macrophages detect microbial invaders and release pro-inflammatory cytokines. Pyrogens have an effect by acting on a certain part of the brain.
Why is it a good idea for a bacterial cell to be able to use glucose FIRST as an energy source (until it is depleted), THEN switch to lactose?
Glucose is an easier compound to break down and obtain energy from than lactose AND for conservation of energy: why use the energy to make the enzymes for breaking down lactose when glucose doesn't need any extra enzymes for breakdown?
Which of the following produces the most precursor metabolites?
Glycolysis
reading frame
Grouping of a stretch of nucleotides into sequential triplets that code for amino acids; an mRNA molecule has three potential reading frames, but only one is typically used in translation.
Why are viroids resistant to nucleases?
Having a circular RNA "genome," they are resistant to most exonucleases (that digest the free ends of RNA or DNA).
In opsonization with IgG, why would it be important that IgG react with the antigen BEFORE a phagocytic cell recognizes the antibody molecule?
If the IgG is bound to the phagocyte BEFORE opsonization, it would most likely be ingested by the phagocyte before it could bind to a pathogen (it would be "naked," so to speak).
Which of the following statements about spontaneous mutation is TRUE?
If the mutation rate to antibiotic A is 10-9 per cell division, and to antibiotic B is 10-6 per cell division, the probability of the cell being resistant to both medications is 10-15.
Which of the following class of antibody is primarily found in external secretions?
IgA
The only class of antibody that can cross the placenta is ______.
IgG
Which class of antibody accounts for most of the circulating antibodies?
IgG
Which of the following antibodies is a pentamer?
IgM
Antibodies bind to flagella preventing movement or to pili preventing attachment of bacteria
Immobilization and prevention of adherence
Autotrophs use carbon dioxide (CO2) to synthesize organic compounds. Which of the following descriptions of this process are true?
In photosynthetic organisms, the process is called the light-independent reactions. It is called carbon fixation. It often involves the Calvin cycle.
Which of the following are physical ways to remove or destroy microbes?
Incineration Ultraviolet radiation Autoclaving Filtration
intercalating agents
Insert between base pairs
CRISPR system
Insertion of small fragments of phage genome into host chromosome, giving the cell a "memory" of previous attempted infection and a way to recognize and destroy that foreign DNA in the future.
Most temperate phages integrate into the host chromosome, whereas some replicate as plasmids. Which kind of relationship do you think would be more likely to maintain the phage in the host cell, and why?
Integration, because plasmids are frequently lost during cell division, which could leave a daughter cell without the virus genome. Correct
______ provides an alternative to heat for sterilization and disinfection, but the process damages some types of plastics.
Irradiation
What is the effect of poisons such as mercury in antimicrobial products? Recall that mercury oxidizes the S-H groups of the amino acid cysteine in proteins, converting it to cystine.
Irreversible non-competitive inhibition—the mercury binds to an allosteric site on the enzyme and permanently changes the shape of the active site, so that the enzyme becomes nonfunctional.
Which of the following statements about complement protein C1 is FALSE?
It cleaves C3 into C3a and C3b.
Which is not true of RNA?
It contains both uracil and thymine.
Is it as effective to take two antibiotics sequentially for an infection as it is to take them simultaneously, as long as the total length of time of the treatment is the same?
It depends. Provided that the majority of the infectious agent is killed off by the first drug, the likelihood that the few that are left would not also be killed by the second drug is low. However, simultaneous treatment should be more effective at eliminating all the microbes in the shortest time possible, and with the least probability of selection for multiple drug resistance mutations.
Does the presence of introns/exons in eukaryotic cells provide more potential diversity in gene products (proteins) than is possible in prokaryotic cells?
It does. Exons/introns can be spliced together in different ways post-transcription to yield different mRNAs (and therefore, different proteins). Bacteria lack this system.
Why is the position of the first AUG after the ribosome binding site critical?
It establishes the reading frame.
Clostridium paradoxum grows optimally at 55°C, pH 9.3; it will not grow in the presence of O2. Please select the TRUE statement about this organism.
It is an obligate anaerobe.
Which is FALSE about the RNA transcript?
It is made in short fragments that are then stitched together.
How does a cytokine function?
It is secreted by a specific cell type and binds to a receptor on target cells causing a signal within that cell that turns on (or off) certain genes to achieve a response.
After mRNA is made, what generally occurs?
It is translated to protein.
Which is true about prokaryotic (bacterial) RNA polymerase?
It is used during transcription.
Which is true of iodine?
It is usually found as tinctures or iodophors.
What would true about an organism called Bacillus fastidiosus?
It might be expected to be very strict in its growth requirements.
What happens to an organism if it lacks one or more enzymes in a given biosynthetic pathway?
It must have the end product provided from an external source.
Which of the following statements about interferon is incorrect?
It prevents the entry of viruses into nearby cells.
Which is TRUE about a crown gall tumor?
It results from the incorporation of bacterial plasmid DNA into the plant chromosome.
Which of the following is/are a(n) antigen-presenting cell(s)?
Macrophages, dendritic cells, AND B cells
During which phase of the bacterial growth curve does a bacterial population become much more resistant to harmful conditions?
Late log phase
Which of the following are considered physical (versus chemical) factors that contribute to the skin and mucous membranes protective role against infection?
Layers of cells Mucociliary escalator Flushing of urinary tract
Which of the following do not induce a strong immune response?
Lipids AND simple sugars.
Which of the following describes a latent viral infection?
Long periods of time with essentially zero viral replication, punctuated by outbreaks of active replication and disease manifestation. Infected individuals are largely non-infectious between outbreak periods.
Which of the following are secondary lymphoid organs (areas where mature lymphocytes become activated)?
Lymph nodes Peyer's patches Tonsils Spleen
Which is a filamentous phage?
M13
Please identify the incorrect definition.
MHC class II—molecules that cells use to present antigen to cytotoxic T cells.
Which of the following statements about phagocytosis is FALSE?
Macrophages die after phagocytosing bacteria, but neutrophils survive.
Select all of the following that apply to a secondary response to a T-dependent antigen:
May take only 2-4 days to build a substantial amount of antibodies in the bloodstream. Produces mainly either IgG or IgA antibodies without shifting to other types. Fine-tunes and increases strength of binding of antibody to antigen through the process of affinity maturation.
What would be a "good" argument against Spallanzani's experiment and in support of spontaneous generation?
Melting the flask neck closed kept the "vital forces" from entering and prevented spontaneous generation of life.CorrectCorrect
Phagocytes were first discovered and named by
Metchnikoff
Restriction-modification systems.
Modifying self-DNA shortly after it's produced, followed by using restriction endonucleases to digest DNA that lacks modification.
The body's own cells do not trigger the alternative pathway of complement system activation. Why is this?
Molecules in host cell membranes bind regulatory proteins that will inactivate any C3b molecules that attach to the membrane.Correct
Which of the following are referred to as mononuclear phagocytes?
Monocytes and macrophages
A soil sample is placed in liquid and the number of bacteria in the sample is determined using two methods: (1) colony count and (2) direct microscopic count. How would the results compare?
More bacteria would be estimated using the direct microscopic count and less bacteria would be estimated using the colony count.
Phenolic compounds are effective against ______.
Most vegetative bacterial cells
Which of the following bacteria lack(s) a peptidoglycan cell wall?
Mycoplasma pneumoniae
The amino acid that is placed first during translation in bacteria, mitochondria, and chloroplasts is
N-formyl-methionine.
The electron transport chain is a cluster of membrane-embedded electron carriers that accept electrons from the coenzymes _______ and _________ and then pass these electrons along the chain.
NADH and FADH2
Which of the following combinations of molecules is produced during the light-dependent reactions of photosynthesis and used in the light-independent reactions?
NADPH and ATP
dentify all the statements that describe the benefits of microbes from a human perspective.
Nitrogen gas is not accessible for use by most organisms without the help of some microbes. Today's environmental oxygen levels may be a direct result of photosynthetic microbes. Microbes degrade/recycle metabolic wastes from other living organisms.
An antibiotic is added to a culture of E. coli, resulting in death of the cells. Bacteriophages are then added. Would the phages replicate in the E. coli cells? Why or why not?
No, because the bacteriophages would depend too much on having the active machinery of a living host cell for replication.
Viruses are in the domain(s)
None of the answer choices is correct.
Which of the following pairs is NOT correctly matched?
Nonsense mutation—incorrect amino acid
DNA in cells can encode for thousands of different proteins. Why do cells require mechanisms to regulate expression of the genes that code for these proteins?
Not all proteins are needed at all times, or in equal amounts. Regulating their expression saves energy and time.
Would you expect the number of virions to be the same if you measured them by the plaque assay or by counting using the electron microscope? Why?
No—the plaque assay only measures viable virus particles, while the electron microscope cannot distinguish between defective and viable virus.
In the late 1800's, Dr. William Coley, a surgical oncologist, noticed that cancer patients who got an infection after their surgery actually did better than patients who did not. He developed Coley's Toxin, which was a mixture of dead bacteria (Streptococcus pyogenes and Serratia marcescens) that were used to treat cancer patients until the 1950s, when new treatments were being developed. Now that you know that S. enterica has potential for fighting cancer partly by stimulating the patient's own immune system to recognize and destroy cancer cells more effectively, which of the statements about Coley's Toxin could be true?
One of the bacteria used in Coley's Toxin was a Gram-negative organism.
The initial transfer RNA occupies the _____ site on the ribosome.
P site
Lister developed his ideas on prevention of infection during medical procedures after studying the work of
Pasteur.
You are working in a clinical laboratory in a hospital setting. You're handed a throat swab from a patient. You are told specifically that the physician is only interested in the presence and type of Gram positive cells. Identification isn't the main goal here—just a first step to work towards determining what Gram positive cells might be there. What might you do first to go about working towards this goal?
Perform a Gram stain.
It would be useful if antigens were delivered directly to
Peyer's patches AND M cells.
temperate phage
Phage that is able to incorporate its genome into the host chromosome.
virulent phage
Phage that lyses the bacterial host when completing its life cycle.
During a one hour time period in a population of approximately a billion cells, ten cells divide, and a hundred thousand cells die. This pattern suggests the population is experiencing which phase of a growth curve?
Phase of prolonged decline
What three components make up RNA subunits?
Phosphate, nitrogenous base, ribose sugar
You inoculate fern spores onto the surface of a growth medium in Petri dishes and wait for them to develop into gametophytes, a stage in the life cycle of a fern. The medium contains sources of nitrogen, phosphate, and a number of other macro- and micro-nutrients, but no carbon. After a few weeks, you see a contaminant growing on your plates. Assuming the organism is not digesting the agar itself, which of the following is most likely your contaminant?
Photoautotrophic species of bacteria, archaea, or protists.
ou inoculate fern spores onto the surface of a growth medium in Petri dishes and wait for them to develop into gametophytes, a stage in the life cycle of a fern. The medium contains sources of nitrogen, phosphate, and a number of other macro- and micro-nutrients, but no carbon. After a few weeks, you see a contaminant growing on your plates. Assuming the organism is not digesting the agar itself, which of the following is most likely your contaminant?
Photoautotrophic species of bacteria, archaea, or protists.
The family to which the Rhinovirus belongs is the
Picornaviridae.
Which of the following statements about plant virus transmission are TRUE?
Plant viruses enter their host through wounds. Grafted plants may be at risk of virus infection. An insect may transmit viruses between plants. Parasitic fungi may transmit plant viruses.
If you were carrying out a penicillin enrichment culture and you forgot to add penicillinase before plating the sample onto nutrient agar, what would happen?
Prototrophs and auxotrophs would both be killed by the penicillin; only PenR mutants would grow and you would not enrich for auxotrophs.
A common environmental organism that may even grow in certain chemical disinfectants is
Pseudomonas aeruginosa.
What type of programmed cell death also triggers an inflammatory response, recruiting various components of the immune system to the region?
Pyroptosis
Which would be most effective against Pseudomonas?
Radiation
transposons
Randomly insert into DNA
direct microscopic count
Rapid, but at least 10^7 cells/ml must be present to be effectively counted.
Which of these scientists were involved in investigating the idea of spontaneous generation?
Redi and Pasteur
Which of the following about simple and differential staining is CORRECT?
Simple stains use a single color while a differential stain uses more than one color to highlight differences between certain groups of cells.
In which of the following sites would you expect to find normal microbiota?
Skin, vagina, colon
Which of the statements regarding smallpox is TRUE?
Smallpox has been eliminated as a naturally occurring infection in human beings through vaccination.
The scientist that contributed most to the development of pure culture techniques was
Robert Koch.
Which of the following types of repair does not require the standard DNA polymerase with proofreading capability?
SOS repair
which of the following repair mechanisms is the most error-prone
SOS repair
Thymine dimers are removed by
SOS repair, photoreactivation repair, AND excision repair.
ribosome binding site
Sequence of nucleotides in mRNA to which a ribosome binds; the first time the codon for methionine (AUG) appears after that site, translation generally begins.
How do some pathogens prevent complement activation or avoid the effects of activated complement?
Some pathogens hijack the host's regulatory membrane proteins that inactivate C3b, preventing the triggering of the alternative activation pathway AND some pathogens produce C5a peptidase that destroys complement C5a, a chemoattractant that recruits phagocytes to the area of infection.
Which of the following are reasons that prokaryotic cells may secrete proteins?
Some secreted proteins are enzymes needed for breaking down environmental macromolecules into smaller subunits for transport into the cell. Some secreted proteins make up extracellular appendages such as flagella, which are used for movement.
Which pair is INCORRECT?
Splicing—removal of introns from prokaryote mRNA following transcription.
A skin swab yields cells that appear as clusters of round cells under the light microscope. Given this information, it is possible that the organism is
Staphylococcus aureus OR Staphylococcus epidermidis.
Hexachlorophene has been particularly effective against
Staphylococcus aureus.
Which type of phosphorylation does not require a membrane?
Substrate-level phosphorylation
Which of these is base-paired correctly?
T - A
CD8 cells are
T cytotoxic cells
The receptors found on the T cell in the figure are
T-cell receptors and CD8 proteins
One of the most intensively studied virulent phages which infects E. coli is ______
T4
One of the most intensively studied virulent phages which infects E. coli is ______.
T4
Please select the TRUE statement regarding Toll-like receptors (TLRs).
TLRs allow cells to detect patterns associated with microbes, indicating that the innate immune responses involve some specificity (although not the specificity of adaptive immunity).
Which of the following pattern recognition receptors is/are anchored in the host cell membrane?
TLRs and CLRs
Select all of the statements that apply to a primary response to a T-dependent antigen:
Takes 10-14 days to build a substantial amount of antibodies in the bloodstream. Produces mainly IgM antibodies, but undergoes class switching to other classes near the end of the response. Fine-tunes and increases strength of binding of antibody to antigen through the process of affinity maturation
total weight
Tedious and time-consuming; however, it is one of the best methods for measuring growth of filamentous microorganisms
What happens when a hairpin loop forms in mRNA
The RNA polymerase and the mRNA dissociate from the DNA
Smoking impairs the ciliated cells of the middle portion of the respiratory tract. Many analgesic drugs (painkillers) impair peristalsis (the churning motion of the digestive tract). The result of either of these activities leads to an increased risk of infection in their respective areas. Why?
The actions of the cells in these areas help to propel pathogens out of the area, serving as a part of the physical barrier system. When they are impaired/slowed, bacteria and other pathogens have an easier time adhering to the tissues in the area and causing an infection.Correct
How would cellulose-degrading bacteria in the rumen (stomachs) of a cow benefit the animal?
The bacteria would produce, secrete, and incorporate organic molecules as they obtain energy from the cellulose in grass and replicate. The cow could then digest both the secreted organic molecules AND the bacteria that synthesized them.
A bacterial strain is resistant to infection by a bacteriophage. Which statement is FALSE?
The bacterial host DNA is protected from restriction enzyme degradation by phosphorylation.
What would be the consequence of a transposon inserting into the site shown by the red arrow?
The bacterium would likely become sensitive to tetracycline.
Consider the following linear metabolic pathway of a bacterial cell: Starting compound → Intermediate-a → Intermediate-b → End Product. The first two reactions are catalyzed by enzymes A and B, respectively. If a mutant cell arose that was unable to produce enzyme B, what would be the impact on the other components of the pathway?
The cell could still produce intermediate-a but would be unable to produce intermediate-b or the end product.
In direct selection methods used to identify possible carcinogens (example: Ames testing), what does it mean when a chemical can cause a bacterium to develop resistance to some environmental condition?
The chemical is a mutagen.
The researcher inoculates the test population of bacteria onto glucose salts agar containing penicillin and also on nutrient agar containing penicillin. She counts 25 colonies on the glucose salts plate lacking histidine and 32 colonies on the nutrient agar. Which of the following statements is TRUE?
The colonies on both plates contain penicillin-resistant mutants. The glucose salts plate contains some mutants.
replisome
The complex of enzymes and other proteins that synthesize DNA
What feature of the eukaryotic cytoplasmic membrane differentiates it the most from the prokaryotic cytoplasmic membrane?
The composition of the phospholipid layer facing the outside of the cell is significantly different compared to the lipid layer facing the cytoplasm.
What is the active site of an enzyme?
The critical site to which a substrate binds by weak forces.
Syphilis, an STI, was once treated by intentionally infecting the patient with the parasite that causes malaria, a disease characterized by repeated bouts of fever, shaking, and chills. Why might this treatment cure syphilis?
The effect of driving up the body temperature for periods of time can shut down the temperature-sensitive replication of the bacterium that causes syphilis. This gives the immune system time to eliminate it properly.
Oxidative phosphorylation, the mechanism by which cellular respiration uses the NADH and FADH2 generated in glycolysis, the transition step, and the TCA cycle to synthesize ATP, involves what two steps?
The electron transport chain generates a proton motive force. ATP synthase uses the energy of the proton motive force to drive the synthesis of ATP.
What is one disadvantage of using heat treatment to sterilize plastic items?
The items may melt.
Which statement about normal microbiota is TRUE?
The microbiome includes members of a microbial community and the genetic makeup of that community.
What component of RNA is different from one person (or one bacterium) to the next?
The order of nitrogenous bases
You are analyzing a bacterial genome. You find that the G-C content is 60%. However, in one part of the genome, the G-C content is 37%. What can you conclude?
The organism has a genomic island.
A research laboratory is investigating environmental factors that would inhibit the growth of Archaea. One question they have is whether adding the antibiotic penicillin would be effective in controlling their growth. What do you think the outcome would be if they tried this?
The penicillin wouldn't affect the Archaea because it prevents cross-linking of peptidoglycan and Archaea don't have this compound in their cell walls.
You add an unknown phage to a mixture of F+ and F− cells of E. coli and plate out the bacteria. The bacterial colonies that grow are all F−. How can you explain this phenomenon?
The phage bound to a receptor on the sex pilus, and therefore only infected the F+ cells (leaving the F− cells alone).
Fats are hydrolyzed by lipases. The glycerol component is then converted to a precursor metabolite, and the fatty acids are degraded using a series of reactions called β-oxidation that remove successive 2-carbon units. Where do these components enter the central metabolic pathways for further oxidation?
The precursor metabolites from glycerol enter glycolysis; the 2-carbon units from fatty acids are added to coenzyme A and enter the TCA cycle.
Which of the following is the definition of clonal selection?
The process in which a lymphocyte's antigen receptor binds to an antigen, allowing the lymphocyte to multiply.
Select the FALSE statement regarding the proton motor force.
The proton motive force involves moving electrons from one side of the nuclear membrane to the other.
anticodon
The sequence of three nucleotides in a tRNA molecule that is complementary to a particular codon in mRNA. the anticodon allows the tRNA to recognize and bind to the appropriate codon
Why is translation needed?
The subunits of nucleic acids are nucleotides, while those of proteins are amino acids
What about Pasteur's experimental design was uniquely directed at dismissing the notion of "vital forces" and spontaneous generation?
The swan-neck flasks, which allowed "vital force" but not microbes to enter the broth.
Which is the best definition of generation time?
The time it takes for the number of cells in a population to double
Two bacterial genes are transduced simultaneously. What does this suggest about the location of the two genes relative to each other?
The two genes must be close together on the bacterial chromosome
Which is (are) true regarding organic acids?
They are weak acids. They are often involved in metabolic reactions. They often exist in the ionized form at the near-neutral pH found in a cell.Incorrect Pyruvate and pyruvic acid refer to different forms of the same substance.
Microorganisms can grow on a variety of organic compounds other than glucose, including polysaccharides, proteins, and lipids. How do they accomplish this?
They break these macromolecules down into appropriate precursor metabolites that are then introduced into central metabolism or used in biosynthesis.
In photosynthesis, what do the light reactions, or light-dependent reactions, accomplish?
They capture radiant energy and convert it to chemical energy in the form of ATP.
Which of the following are advantages of using alcohol solutions for disinfection?
They do not leave a residue.
Select the TRUE statements regarding reverse-transcribing viruses.
They have a unique enzyme called reverse transcriptase. Their replication strategy goes against the central dogma of genetics. They exhibit high mutation rates in their genomes.
Some bacteria have a higher incidence rate of thymine dimer mutations following exposure to UV light than others. What might be going on here to lead to this outcome?
They may simply have a higher proportion of T nucleotides next to each other in their DNA than other bacteria, leading to more possible dimers being formed AND they may have a weaker expression of photoreactivation enzymes, leading to formation of more thymine dimers.
Which nucleotide is not found in RNA?
Thymine
plate count
Time-consuming but technically simple method that does not require sophisticated equipment. Generally used only if the sample has at least 10^2 cells/ml
What does the word "transcribe" mean?
To make a copy
generalized transduction
Transduction resulting from a packaging error
specialized transduction
Transduction resulting from an error in excision of a prophage.
For each six-carbon molecule of glucose that enters glycolysis, how many molecules of pyruvate are made, and how many carbon atoms does each pyruvate have?
Two molecules of pyruvate, each with three carbon atoms.
messenger rna (mRNA)
Type of RNA molecule translated during protein synthesis
If a DNA triplet is AGT, the mRNA codon would be ______ and the tRNA anticodon would be ______.
UCA; AGU
If one strand of DNA contains the bases ACAGT, what would be the complementary bases on the mRNA strand?
UGUCA
The formation of a covalent bond between two adjacent thymines is caused by
UV radiation.
Please select the methods that are used to cultivate animal viruses.
Use of cell culture techniques. Use of animal inoculation. Inoculation of embryonated eggs.
base analogs
Used in place of normal nucleobases
Which of the statements about immunofluorescence is not true?
Uses the dye methylene blue.
You are in charge of water quality for your city's water treatment plant. Of the methods at your disposal, which will be the most efficient and cheapest method of determining the number of viable bacteria in the water coming out of your plant?
Using membrane filtration followed by placing the membrane in a growth medium for colony counts after incubation.
The word "animalcule" was first used by ______.
Van Leeuwenhoek
Scientists recently cloned Louis Pasteur and put him to work in a modern lab. He immediately developed a topical gel (used externally) that breaks down proteins. Since he hasn't been around for some time, he's unsure what the best application for his invention might be. Help him out. What pathogenic agent would this gel be most effective and safe at eliminating?
Viruses on the surface of the skin.
Which is true of simple diffusion of water?
Water usually enters a cell and produces a high osmotic pressure.
Why would it be beneficial for cells to wait until a critical population density is reached before expressing certain genes?
Without a certain density, it would be highly unlikely that the molecules produced by a cell in the group could find and bind to other cells of the population effectively.
Why is the process of gene rearrangement used in creating antibodies and T-cell receptors (TCRs) so important?
Without it, we would need a single gene for every antibody and TCR required to mount all the possible responses needed during our lives.
The study of the crown gall tumor found
a bacterial plasmid promoter that was similar to plant promoters.
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
a plaque.
all of the following are involved in DNA replication except: a polysome gyrase primase polymerase a primer
a polysome
all of the following are involved in transcription except: polymerase a primer a promoter a sigma factor uracil
a primer
all of the following are directly involved in translation except: a promoter ribosomes a start codon a stop codon tRNA's
a promoter
The F pilus is
a protein appendage that attaches the two cells together.
An open reading frame or a possible protein-encoding region of prokaryotic DNA is
a region of DNA that begins with a start codon (ATG) and ends with a stop codon.
In the absence of lactose,
a repressor protein binds to the operator.
MacConkey agar is
a selective and differential medium.
codon
a series of three nucleotides that code for a specific amino acid
Plasmids are
able to replicate independently of the chromosome.
Does "spontaneous generation" make sense to people from ancient times?
absolutely
Identify the differential staining method that is most important in the diagnosis of tuberculosis.
acid-fast
Intercalating agents
act during DNA synthesis AND often result in frameshift mutations.
In the absence of lactose, the lac repressor is
active and can bind to the operator.
The critical site of an enzyme to which a substrate binds by weak forces is called the
active site
Infection in which a virus multiplies rapidly and spreads in the host.
acute infection
In a quantal assay, animal viruses are quantified by
administering several dilutions of a virus preparation to a number of animals, cells, or chick embryos, then determining the dilution that infected/killed 50% of the group.
Cells can quickly alter the activity of certain key enzymes, using other molecules that bind reversibly and distort them. This control of enzymes is called ________ regulation.
allosteric
Clusters of differentiation (CD) molecules are important because they
allow us to differentiate between cells that may look identical by microscopy.
Aldehydes typically kill microbes by ______.
altering nucleic acids altering proteins
The complement pathway that is activated by binding of C3b to cell surfaces is the
alternate pathway
Phase variation is a phenomenon used by some bacteria (such as E. coli) to evade host immune mechanisms. In this process, the cells
alternately turn genes on/off to adjust bacterial behavior.
Please select three examples of growth factors from the list.
amino acids viatamins nucleotides
the frequency of transfer of an F' molecule by conjugation is closest to the frequency of transfer of
an F plasmid by conjugation
In conjugation the donor cell is recognized by the presence of
an F plasmid.
The plasmid is mobilized for transfer when
an endonuclease cleaves it at the origin of transfer
The basic parts of a bacteriophage are
an icosohedral head, tail, tail pins, and fibers
The humoral immune response is delivered by
antibodies
All of the following events can occur after complement activation except
antibody production
Macrophages and dendritic cells are
antigen presenting cells
Genetic exchange in segmented viruses that allows a zoonotic virus to infect humans is an example
antigenic shift.
You are setting up an enrichment culture to look for methylotrophic bacteria in a sample of water from Lake Washington in Seattle. Methylotrophs are capable of obtaining their carbon and energy needs from single carbon compounds such as methanol. In your enrichment culture, you provide methanol and a variety of macro- and micro-nutrients to encourage growth. However, which of the following must you leave out if you are to successfully enrich for methylotrophs?
any other carbon source
Competent cells
are able to take up naked DNA, occur naturally, AND can be created in the laboratory.
filamentous phages
are extruded from the host cell
The term "precursor metabolite" refers to molecules that
are used in biosynthesis.
High concentrations of salt and sugar in foods
are useful in preserving the food AND tend to draw water out of a cell.
Repressible operons (such as the arg operon)
are usually in the "on" mode.
It is often difficult to choose which germicide to use because often the most effective options ______.
aren't safe
Which of the following statements about bacteria is FALSE?
as a group, bacteria are very well characterized
Nucleotide subunits of DNA and RNA are composed of three units: a 5-carbon sugar, a phosphate group, and a nucleobase. They are initially synthesized ______. Multiple choice question.
as ribonucleotides that can be converted to deoxyribonucleotides by replacing the 2' hydroxyl group with a hydrogen atom
The sugar component of RNA and DNA nucleotides is synthesized
as ribose and then changed to deoxyribose.
In the cultivation of microaerophilic and anaerobic bacteria,
atmospheric oxygen in a(n) candle/anaerobe jar is converted to water.
Individual atoms on the surface of prepared samples can be observed by using the
atomic force microscope
Viral spikes
attach specifically to host cell receptors
the tail fibers on phages are associated with
attachment
The stage of T4 replication that involves interaction between the protein fibers on the phage and receptors on the bacterial cell wall is the
attachment stage
The correct order for the stages of a phage infection is
attachment, penetration, transcription, replication of nucleic acid and protein, assembly, release
Which does not refer to the shape of a virus?
bacillus
Transducing virulent phages do not lyse the cells they invade because
bacterial DNA has replaced critical viral DNA in the phage.
adding DNase to a mixture of donor and recipient cells will prevent gene transfer via
bacterial transformation
A virus that infects bacterial cells is called a ______.
bacteriophage
Viruses that infect bacterial cells are called ______.
bacteriophages
Silver is used as an antimicrobial in which of the following products?
bandage pads burn creams
Bacteria on fish caught in the Arctic Ocean would
be psychrophiles AND would continue to grow while the fish is in the refrigerator.
Father Spallazani repeated John Needham's experiment but Spallazani boiled the broth for much longer and sealed the flasks by melting their necks closed. He observed that the broth remained sterile, basically forever. What do you think the vast majority of the people believed from his experiment?
because the flask was sealed, the vital forces could not enter the flask
If conditions are favorable, the generation time of bacteria
can be as short as 30 minutes
Antigenic variation is a phenomenon used by some bacteria (such as Neisseria gonorrhoeae) to evade host immune mechanisms. In this process, the cells
can change the characteristics of certain surface proteins on the bacteria, forcing immune response to constantly adapt.
A positive (+) strand of RNA
can directly act as mRNA.
When the bacteriophage transfers bacterial DNA into a recipient bacterial cell, that DNA
can integrate into the chromosome
When the bacteriophage transfers bacterial DNA into a recipient bacterial cell, this DNA
can integrate into the chromosome
Expression of viral oncogenes in infected animal cells
can mimic proto-oncogenes, causing imbalance in cell cycle control towards unchecked proliferation, leading to tumor formation.
The process by which chemolithoautotrophs and photoautotrophs incorporate CO2 into organic compounds is called
carbon fixation
The energy released by ______ is captured by cells to make ATP; this ATP can then be used for biosynthesis, or ______.
catabolism;anabolism
Enzymes are biological ______ that are typically _______.
catalysts; protein
Quaternary ammonium compounds (quats) are ______. Multiple choice question.
cationic detergents that help wash surfaces
Microorganisms are useful for all of the following EXCEPT
causing disease
Adding sorbic, propionic, and benzoic acid to foods affects ______ of microbes.
cell membranes
High pressure (130,000 psi) is thought to kill microbes by altering their ______.
cell membranes proteins
The target of penicillin in bacterial cells is ______.
cell wall
Cytotoxic T cells primarily are responsible for
cell-mediated immunity.
Plants are dependent on microorganisms for
changing atmospheric nitrogen to a usable form.
The attraction of leukocytes to the area of inflammation is referred to as
chemotaxis
5'AUG3'
codes for methionine AND determines the reading frame.
A stop codon
codes for no amino acid.
_____ are groups of three bases in mRNA that specify one amino acid in the amino acid chain.
codons
Some enzymes act with the assistance of a non-protein component. This component is called a ____, if that component is an organic molecule it can be called a _______
cofactor; coenzyme
Which of the following is a bacterial product?
colicin
You have a culture of bacteria in which cells are dying off at a constant rate. This culture is most likely in ______ phase.
death
The compounds secreted or delivered by the T cell shown in the figure lead to
death of the infected cell. alerting neighboring cells to the presence of virus.
Phenolics
denature proteins and destroy cytoplasmic membranes.
Commercial canning processes
destroy Clostridium botulinum spores, are especially needed on low acid foods, AND are 12D processes (designed to kill 1012 endospores).
Low-level disinfectant
destroy fungi, vegetative bacteria except mycobacteria, and enveloped viruses. also called general purpose, used for disinfecting furniture and floors in hospital.
intermediate level disinfectants
destroy vegetative bacteria, mycobacteria, fungi, and most viruses Disinfect non-critical instruments
Gregor Mendel
determined that traits are inherited as physical units, now called genes
Upon treatment with heat or chemicals, bacteria will
die at a constant proportion.
What general type of staining is used to separate various types of bacteria based on their cellular structures?
differential
Cells constantly produce ATP during the ______ reactions of ______, and use it to power _______ reactions of _______
exergenic, catabolism, endergenic, anabolism
Cationic detergents typically work by _____
disrupting the cell membrane
origin of replication
distinct region of a DNA molecule at which replication is initiated
During the development of both B and T cells, a process called negative selection occurs. This is necessary because it helps ensure that the cells
do not recognize "self" molecules.
The phages T4 (lytic) and lambda (temperate) share all of the following characteristics EXCEPT
existing as a prophage
One bacterial chromosome replicates to become two chromosomes with
each made of one strand of DNA from the original chromosome and one newly synthesized strand.
Toll-like receptors
each recognize a specific "danger" molecule AND are embedded in cellular membranes.
Radio waves, X-rays, microwaves, UV light and gamma rays are all examples of ______.
electromagnetic radiation
In oxidative phosphorylation, quinones, cytochromes, and flavoproteins are all ______ carriers.
electron
In addition to four protein complexes, the mitochondrial electron transport chain has two freely-moving ______, ubiquinone and cytochrome c, that serve to ______.
electron carriers; shuttle electrons between the complexes
The most highly resistant microbial structure is the bacterial
endospore
Which of the following is found exclusively in prokaryotic cells?
endospore
Hydrogen sulfide is produced as a result of certain types of anaerobic respiration. Some chemolithotrophs can then use this as a/an ______.
energy source
Chemolithoautotrophs
energy source: inorganic chemicals (H2, NH3, NO2-) carbon source: CO2
photoautotroph
energy source: light carbon source: CO2
Photoheterotrophs
energy source: light carbon source: organic compounds
Chemoorganoheterotrophs
energy source: organic compounds (sugars, amino acids, etc) carbon source: organic compounds
Consider how cells obtain energy to make ATP. The chemical that serves as the electron donor is the _______ source, and and the one that ultimately accepts those electrons is the ______ electron acceptor
energy; terminal
Binding of an activator to an activator binding site on DNA
enhances the ability of RNA polymerase to bind to the promoter site.
Please choose the term that describes a virus that has a lipid bilayer (derived from the host cell) surrounding its capsid.
enveloped virus
The use of the suffix "ase" on a word denotes a(n)
enzyme
dna ligase
enzyme that joins two DNA fragments together by forming a covalent bond between the sugar and phosphate residues of adjacent nucleotides
rna polymerase
enzyme that synthesizes RNA using one strand of DNA as a template
primase
enzyme that synthesizes small fragments of RNA to serve as primers for DNA synthesis
Proteins that function as biological catalysts are called
enzymes
One advantage of having genetic control mechanisms is
enzymes are only produced when they are needed.
Generally, membrane filters are not used to remove
enzymes from liquids.
All of the following accurately describe enzymes EXCEPT ______.
enzymes provide energy to help reactions proceed more rapidly
Enveloped viruses
have a lipid bilayer membrane containing various proteins.
A segment of DNA encoding a protein or an RNA molecule is a ______.
gene
genotype
genetic makeup of an organism
Select the statement that most accurately defines the strain in a scientific name.
genetic varients within a species
The simultaneous regulation of many bacterial genes is
global control.
In the case of plants, algae, and cyanobacteria, the two major products of photosynthesis are ______.
glucose and oxygen
The lac operon is expressed when
glucose is low and lactose is present.
glucose-salts broth (chemically defined medium)
glucose, dipotassium phosphate, monopotassium phosphate, magnesium sulfate, ammonium sulfate, calcium chloride, iron sulfate, water
Starch and cellulose are both polymers made up of the monosaccharide ______, which means that hydrolysis of the polymers releases subunits that can enter directly into the central metabolic pathway of ______ to be oxidized.
glucose; glycolysis
A 2% solution of ______ is used as a liquid chemical sterilant for treating heat-sensitive medical items. Multiple choice question.
glutaraldehyde
Fats, the most common simple lipids, are broken down by lipases into their component ______.
glycerol and fatty acids
Lipid synthesis generally requires the components _______ and ______ acids.
glycerol; fatty
Microorganisms that can grow on polysaccharides and disaccharides first break these down to glucose or precursor metabolites that can then enter into the pathway of ______ to be oxidized.
glycolysis
The primary pathway used by many organisms to convert glucose to pyruvate is
glycolysis
Which of the following are most susceptible to complement lysis?
gram - bacteria
Penicillin would be most effective against
growing bacteria AND Gram-positive bacteria.
Small organic molecules that must be provided to bacteria in order for them to grow are called
growth factors.
Which of the following is most abundant in bacterial cells?
h2o
Chlorine and iodine are common disinfectants that belong to a class of chemicals called
halogens
You discover a new pathogen which you visualize using a light microscope. A negative stain reveals a clear halo around the cells. This suggests to you that the organism
has a capsule.
influenza vaccines must be changed yearly because the amino acid sequence of the viral proteins changes gradually over time. based on this information, which is the most logical conclusion? The influenza virus...
has an RNA genome
Atoms that are more electronegative than others ______.
have a higher affinity for electrons
In terms of their metabolism, prokaryotes are _______ with respect to compounds they use for energy and _______ in their biosynthetic processes.
highly diverse; remarkably similar
Cells that are His-, StrR could be isolated from a mixed sample by using a medium containing
histidine AND streptomycin
The proofreading function of DNA polymerase reduces the error rate from about one in a million base pairs to about one in a ______ base pairs.
hundred million
The two strands of DNA are joined to each other or held together by
hydrogen bonding
Chemical mutagens often act by altering the
hydrogen bonding properties of the nucleobase.
These dimers weaken ______ between bases.
hydrogen bonds
The electron transport chain is a group of membrane-embedded carriers that pass electrons from one to the next, while simultaneously pumping ______ across the membrane, generating a(n) ______.
hydrogen ions; proton motive force
Salting and drying decrease the availability of water in food, resulting in an environment that is ______ relative to microbes, thereby preventing their growth.
hypertonic
SOS repair, photoreactivation repair, AND excision repair.
in both eukaryotes and prokaryotes.
Purines and pyrimidines are synthesized ______.
in distinctively different manners
Viruses may only be grown
in living cells
Plasmid DNA is transferred
in single-stranded form.
Synthesis of mRNA is
in the 5' to 3' direction with new nucleotides being added to the 3' end of the mRNA molecule.
T-independent antigens
include polysaccharides.
Trace elements
include zinc, copper, and manganese AND may be needed for enzyme function.
The Calvin cycle ______.
incorporates CO2 into organic compounds
Lyme disease is an example of a disease that is due to
increased interaction between humans and tick-carrying animals.
The molecules that bind to a repressor and cause it to no longer bind to the operator are called
inducers
The presence of long double-stranded RNA (> 30 bp)
induces synthesis of interferon.
Viruses are best described as _______.
infectious agents
The first host response to a nonspecific tissue injury is described as
inflammation
C3a and C5a are involved in
inflammation AND attraction of phagocytes.
How does bacteriophage DNA get into the host cell?
injected
The low molecular weight protein produced by animal cells in response to viral infections is
interferon.
Quorum sensing
involves the production and monitoring of signaling molecules AND is used by bacteria to sense the density of cells within their population.
Moist heat kills microorganisms by
irreversible denaturation of proteins.
You discover a new microbe that contains peptidoglycan. Based on this information, the most logical conclusion you can draw about the organism is that it
is a bacterium
The nucleus
is a double membrane sac containing DNA and is found in eukaryotes.
The cytoskeleton
is a dynamic structure composed of microtubules, microfilaments, and intermediate filaments.
Apoptosis
is a form of programmed cell death AND is induced in target cells by effector T cytotoxic cells.
Ozone ______.
is a strong oxidizing agent
Feedback inhibition
is a way of regulating the amount of product produced.
In the article, we learn that S. enterica has lipopolysaccharide. This tells us that the organism
is gram negative
Glucose
is preferentially used over lactose in E. coli as a result of catabolite repression AND glucose levels are the inverse of cAMP levels. Correct
Phagocytosis
is the ingestion of particles and may be performed by animal cells
The P-site
is the peptidyl site on the ribosome.
Pasteurization
is the use of heat to reduce numbers of pathogenic/spoilage bacteria in a food item to a safe level.Correct
Proton motive force
is used to synthesize ATP.
The negative (-) sense strand of RNA
is used to synthesize more (+) strands.
Replica plating
is useful for identifying auxotrophs AND uses media on which the mutant will not grow but the parental cell type will.
The energy yield of any energy-transforming pathway
is variable depending on the amount of precursor metabolites removed for biosynthesis.Correct
Glutaraldehyde
is very good for use on heat-sensitive medical items.
Ethylene oxide is gaseous agent that ______.
is very useful for sterilizing heat- or moisture-sensitive items
When a repressor binds to the operator site on DNA,
it blocks RNA polymerase binding and mRNA synthesis
Francisco Redi performed an experiment in which he put meat in jars, covering some with gauze and leaving others open. He then observed the meat over a few days. While this experiment is very well known in biology, it still did not completely change everyone's belief in spontaneous generation. How was the experiment lacking?
it didnt explain that meat could still "rot"
In transduction, bacterial DNA is transferred to a new cell when
it is injected by the virus carrying bacterial DNA
In an inducible operon, when a substrate or inducer is present,
it reacts with the repressor and inactivates it.
Which of the following is NOT an antimicrobial substance?
keratin
Penicillin enrichment of mutants works on the principle that the antibiotic:
kills only growing cells
Resistance of some animals to certain viral diseases is based on
lack of specific receptors on the host cell.
under which of the following conditions will transcription of the lac operon occur
lactose present/glucose absent
Which of the following are heavy metal pollutants?
lead cadmium mercury iron copper
An atom that has a lower affinity for electrons than another is ______ than the other.
less electronegative
Microorganisms that are free living are ______ to chemical disinfectants than microorganisms in a biofilm.
less resistant
The cells primarily involved in all immune responses are the
leukocytes
Spontaneous generation can be explained as
life arising from dead matter
The prefix photo- indicates that an organism will make use of ______ for energy purposes.
light
Metabolic pathways can be
linear, branched, cyclic
In addition to glucose, which of the following organic compounds can serve as energy sources for microbes?
lipids fatty acids disaccharides monosaccharides proteins polysaccharides
The idea of spontaneous generation postulated that
living organisms could spontaneously arise from non-living material.
A solution of sodium hypochlorite is more effective against bacteria at _______ pH.
low
Which of the following is not typical of an antigen?
low molecular weight
The cells responsible for adaptive immunity are the
lymphocytes
After beta phage infects Corynebacterium diphtheriae and integrates its DNA into the host genome, the bacterium is capable of causing the disease diphtheria. Which term best describes this phenomenon?
lysogenic conversion
Bacteriophages involved in generalized transduction are ______ phages.
lytic
Viral cycles that end in release of the new phages and immediate destruction of the host bacterial cell are referred to as ______.
lytic
Allergic reactions mainly involve
mast cells
In nature, bacteria
may adhere to surfaces by means of pili and slime layers.
Normal tissue taken from animals and prepared immediately as a medium for viral growth is termed a(n)
primary culture.
If an infectious agent is composed only of amino acids, to which group does it belong?
prions
Only antigen-presenting cells
produce MHC class II molecules.
Interleukins are
produced by leukocytes AND protein molecules.
Gamma rays cause biological damage in living systems by
producing reactive molecules such as superoxide and hydroxyl-free radicals.
What is apoptosis?
programmed cell death
Some members of which of the following groups can use inorganic chemicals such as hydrogen sulfide and ammonia for energy?
prokaryotes only
Transcription begins when RNA polymerase binds to the
promoter on DNA.
capsids are composed of
protein
When boiling or pasteurizing a sample, microorganisms are destroyed because their ______.
proteins are irreversibly denatured
Antibiotics
provide an environment in which preexisting mutants survive.
in the ames test, the purpose of adding liver extract is to
provide mammalin enzymes that sometimes alter chemicals
Glycolysis, the Entner-Duodoroff pathway, and the pentose phosphate pathway all produce
pyruvate
Aqueous solutions of ethyl or isopropyl alcohol are commonly used as antiseptics and disinfectants because they ______.
quickly kill vegetative bacteria and fungi are relatively non-toxic do not leave a residue are relatively inexpensive
Toll-like receptors (TLRs) bind molecules on pathogens. This is helpful to the immune response because TLRs
recognize broad categories of molecules that should not be in our system, as we don't have these molecules on our own cells.
The term antiparallel
refers to the opposite orientation of the two strands in DNA.
Phage DNA encodes for the proteins of the viral capsid and
regulatory proteins that direct the production and assembly of the capsid proteins
Which of the following is a function of the mucociliary escalator?
remove microbes from the respiratory tract
you are trying to isolate a mutant of wild type e-coli that requires histidine for growth. this can be done using
replica plating
An enzyme used to synthesize the amino acid tryptophan is most likely
repressible
The electron transport system
requires a membrane AND generates a concentration gradient of protons.
DNA polymerase
requires a template for the synthesis of DNA
Generally the proteins of thermophiles
resist denaturation.
Phage that is able to incorporate its genome into the host chromosome.
temperate phage
Phages that can either replicate and cause cell lysis or can integrate their DNA into the host DNA are called
temperate phages
The environmental factor that influences bacterial growth the most is
temperature
All of the following are true about DNA sequence analysis EXCEPT
the (−) strand of DNA is used.
If a TC encountered a TH cell infected with a virus,
the TC cell would induce apoptosis in the TH cell.
Choose which of the following results Pasteur might have obtained if the broth in his swan-necked flask experiment had contained endospores.
the broth would seem sterile after boiling but would soon grow bacteria
genome
the complete set of genes or genetic material present in a cell or virus
dna replication
the duplication of a DNA molecule
These dimers are repaired by
the enzyme DNA photolyase and exposure to light.
Proton motive force is ______.
the form of energy that results from the electrochemical gradient established by the electron transport chain
Microwaves do not kill organisms directly but kill by
the heat they generate in a product.
In viral entry by endocytosis
the host cell's cytoplasmic membrane surrounds the whole virion and forms a vesicle
The safe temperature ranges for the storage of foods are determined by
the low temperature at which microbes stop multiplying and the high temperature at which they die.
all of the following are characteristics of eukaryotic gene expression except
the mRNA is often polycistronic
Alcohol-based solutions of certain antimicrobial chemicals like iodine are called
tincture
The function of the secretory component of the IgA molecule is
to protect IgA from being destroyed by proteolytic enzymes.
Direct selection involves inoculating cells onto growth media on/in which
the mutant but not the parental cell type will grow.
Thioglycolate medium is used to determine the oxygen requirements of a microorganism. You inoculate a tube of this medium with a bacterium and observe dense growth at the bottom of the tube. From this you can conclude that
the organism is an obligate anaerobe.
Antigens interact with antibodies at
the outer end of each arm of the Y.
translation
the process by which the information carried by mRNA is used to synthesize the encoded protein
transcription
the process by which the information in a strand of DNA is copied into a new molecule of messenger RNA (mRNA)
After the conjugation of an Hfr cell with an F- cell,
the recipient remains F-.
When an amino acid such as arginine binds to a repressor,
the repressor binds to the operator site.
If Pasteur had done his experiments investigating spontaneous generation in a horse stable,
the results would probably have supported the idea of spontaneous generation.
phenotype
the set of observable characteristics
The F plasmid carries the information for
the sex pilus.
Two different mechanisms for copying the DNA strands are used because
the strands are oriented in opposite directions
Translation is needed because
the subunits of DNA and RNA are nucleotides while those of protein are amino acids
The process of transcription is similar to
the synthesis of the leading strand during DNA replication.
The main advantage for bacteria that have the ability to carry out conjugation and other forms of genetic exchange is that
they become genetically diverse.
Bacteria are useful to study because
they have the same fundamental metabolic and genetic properties as higher organisms.
Which is usually NOT true of archaea?
they reproduce by mitosis
Certain intermediates of catabolic pathways, called precursor metabolites, are important because _____
they serve as carbon skeletons from which subunits of macromolecules can be made
HIV/AIDS can be categorized as a new or emerging infectious disease. By putting it into this category, we are indicating that
this infection hasn't been observed in the human population prior to recent (within the last 50 years) outbreaks.
Irradiation of cells with ultraviolet light may cause
thymine dimers.
Removal of the capsid to release the virus nucleic acid into the host cytoplasm is called ______.
uncoating
Retroviruses are unique in that they
use RNA as a template to make DNA.
Giant cells are
used to contain bacterial infections.
membrane filtration
used to count microorganisms in liquid samples that contain relatively few cells
viable cell counts
used to determine the number of cells capable of growing in a given set of conditions.
direct cell counts
used to determine total number of cells; counts include living and dead cells
RNAi
uses short pieces of single-stranded RNA to direct the degradation of specific RNA transcripts
Bioremediation refers to
using bacteria to clean up environmental pollutants.
Germicidal chemicals ______.
usually react irreversibly with proteins, DNA, cytoplasmic membranes, or viral envelopes are often poorly understood with regards to mechanisms of action
turbidity
very rapid method; used routinely. one time correlation with plate counts is rquired for turbidity to be used in determining cell number.
A _______ is a single virus particle.
virion
You discover an agent that multiplies in plant cells and is composed of RNA but nothing else. This agent would be a ______.
viroid
Phage that lyses the bacterial host when completing its life cycle.
virulent phage
As the pressure in an autoclave increases, the boiling point of ________ also increases, as does the temperature at which _________ forms.
water, steam
A new medication is developed that targets and binds to the lipid A portion of LPS in Gram-negative bacterial cells. This drug shows a high degree of binding and activity against purified lipid A in an experiment carried out in test tubes. Based on this information,
we should next proceed by repeating the experiment in test tubes using intact Gram-negative cells to see if the drug binds with the same strength.
Opsonization is
when complement enhances phagocytosis of bacterium.
A mechanism that blocks transcription
will block the production of mRNA.
Plant viruses may be transmitted by
worms, contaminated seeds, humans, and insects
Which of the following are considered trace elements that are required in such small amounts that most natural environments, including water, have sufficient levels to support microbial growth?
zinc cobalt copper molybdenum maganese
