Exam 1 and 2 Review

Which viral genome is likely to require an RNA-dependent RNA polymerase for transciption upon viral entry?

(-) sense single-stranded RNA

Correctly order the following steps in bacterial conjugation from start to finish.

1. A sex pilus is formed that joins an F+ cell to an F- cell. 2. The sex pilus retracts, and a relaxosome forms. 3. The F factor is nicked at oriT, and one strand starts to transfer into the recipient. 4. DNA polymerase III synthesizes a replacement strand in the donor. 5. The transferred DNA strand circularizes and completes replication.

Order the following events as they occur from beginning to end during DNA replication in a dividing cell.

1. DNA at origin unzips, and two replication forks form. 2. Replisomes synthesize daughter chromosomes bidirectionally. 3. Terminator site is replicated. 4. Septum forms. 5. Daughter cells separate.

Outline the correct sequence of steps to verify the predicted function of a gene from an uncultured organism.

1. DNA is sequenced to identify gene of interest. 2. The gene is inserted into a culturable organism like E.coli. 3. The gene is transcribed. 4. mRNA is translated. 5. The protein is purified. 6. The protein is tested for predicted function.

Rank the following steps in order (from first to last) for obtaining a vaccine to protect against COVID-19.

1. Scientists develop a candidate vaccine. 2. The vaccine is evaluated for safety in humans. 3. The efficacy of the vaccine is investigated. 4. FDA grants approval for use of the vaccine in humans. 5. The vaccine is mass produced and distributed to the public.

Which statement best summarizes the types of genes analyzed and the purposes of those analyses in this large study?

16S rRNA genes were analyzed to identify phyla, while all other genes were analyzed to identify functional categories.

When intracellular levels of tryptophan are low, the _________ stem loop forms, which results in ___________ of transcription.

2:3 / progression

The codon ACU is translated to threonine (Thr). What is the corresponding anticodon?

3'-‐UGA

The genome of SARS-CoV-2 is approximately ___ kb long and encodes __ structural proteins.

30; 4

Florence Nightingale's statistical analysis of the leading causes of mortality of British soldiers convinced the British government to do all the following except A. supply soldiers with additional weapons and ammunition. B. improve the quality of water delivered to soldiers. C. improve the standards of army hospitals. D. improve the ventilation systems in army hospitals and soldiers' living areas.

A. supply soldiers with additional weapons and ammunition.

Cellular synthesis of which of the following would be directly affected by nitrogen limitation?

Amino Acids Nucleotides

What does the bacteriophage T4 possess?

An icosahedral "head" and a helical "neck"

Scientists and their contributions

Antoine Van Leewenhoek: observation of microbes Louis Pasteur: disproved spontaneous generation Robert Koch: developed the Four Postulates Edward Jenner: developed vaccines Alexander Fleming: discovered antiobiotics Ignaz Semmelweis: found the antiseptic agent for doctors to use Joseph Lister: developed carbolic acid to treat wounds and clean surgical instruments Sergei Winogradsky: discovered lithotrophs & developed enrichment cultures and the Winogradsky column

Who is credited with being the first person to view single cell organisms?

Antonie van Leewenhoek

What does analysis of 16S rRNA sequences show?

Archaea are as distant from bacteria as they are from eukaryotes.

If the adjacent tryptophan codons in the trp operon leader sequence are mutated to alanine codons, what is the predicted effect on trp operon regulation?

Attenuation may occur in response to high alanine levels. Attenuation will no longer occur in response to high tryptophan levels.

Most organisms (including you) break down organic compounds to obtain energy and nutritional building blocks. In contrast, chemolithotrophs are prokaryotes that obtain energy through the oxidation of inorganic compounds. Which of the following inorganic molecules would these microbes also need to build macromolecules for new cell material?

CO2

What is the relationship between COVID-19 and SARS-CoV-2?

COVID-19 is a consequence of SARS-CoV-2 infection.

What are the components common to all virions?

Capsid DNA or RNA genome

What is the structure in prokaryotes that performs the same function as mitochondria in eukaryotes?

Cell membrane

Which of the following uses preformed organic molecules for both carbon and energy?

Chemoheterotroph

What is the difference between how class I aminoacyl-tRNA synthetases and class II aminoacyl-tRNA synthetases work, and what would have to be done at the end to produce similarly charged tRNA molecules?

Class I synthetases join the carboxyl group of the amino acid to the 2' OH of the tRNA and then the amino acid has to be moved to the 3' OH, whereas class II synthetases attach at the 3' OH, which is ready to be used directly.

Which enzyme helps pack DNA into the cell by negatively supercoiling DNA?

DNA gyrase

DNA mismatch repair is the primary mechanism for correcting misinserted base pairs caused by

DNA polymerase.

Match each genome with the first polymerase it uses to initiate viral synthesis.

DNA polymerase: Double-stranded DNA Single-stranded DNA Host RNA polymerase: (+) sense single-stranded RNA vRNA polymerase: Double-stranded RNA (-) sense single-stranded RNA Reverse transcriptase: (+) strand RNA retroviruses Double-stranded DNA pararetroviruses

Which of the following is the enzyme complex that catalyzes transcription in bacterial cells?

DNA-dependent RNA polymerase

An early victim of COVID-19 was a 27-year-old African-American female who worked as a cashier at a grocery store. Her case history states that she was overweight and previously diagnosed as a diabetic. Which risk factors most likely led to her developing a severe form of COVID-19 illness?

Diabetes & Obesity

The protein complex that mediates the formation of the septum in a growing bacterium is called the:

Divisome

The start of bacterial replication depends on the increase in the concentration of active ___ , which accumulates during the growth phase of the microbe.

DnaA

Which of the following organisms are not considered microbes? A. Fungi B. Bacteria C. Protozoa D. Viruses E. Mosquitoes

E. Mosquitoes

Which of the following sets of symptoms is most characteristic of COVID-19?

Early fever, cough, and shortness of breath

The first vaccination was performed by ____, and first antibiotic was discovered by___.

Edward Jenner; Alexander Fleming

Which of the following structural elements of the SARS-CoV-2 virus is produced according to the genetic information of the host cell rather than the viral genome?

Envelope phospholipids

Sort the following as either unique to eukaryotic regulation of transcription initiation or characteristic of all domains.

Eukaryotic Only: Mediator enhancers nucleosomes All Domains: activators repressors

(True or False) The Pfizer/BioNtech vaccine for the SARS-CoV-2 virus is an mRNA vaccine. mRNA vaccines work because a section of the viral genome is inserted into our genome where it can then be translated into a protein that is recognized by our immune system.

False

Which of the following mechanisms do prokaryotes use to generate phase variation?

Gene inversions Slipped-strand mispairing

Scientists are continuously advancing our understanding of the importance of the human gut microbiome in health and disease. Which of the following is not a challenge associated with studying the human microbiome?

Genomic sequencing of the gut microbiome cannot be completed if the microorganisms cannot be cultured in the lab.

What controls the entrance to the chamber of chaperone protein GroEL?

GroES

Which characteristic of endospores led to confusion when Tyndall tried to replicate Pasteur's experiments regarding spontaneous generation?

Heat Resistance

Evolution toward pathogenicity may involve which of the following?

Horizontal gene transfer Gene loss Gene acquisition

Lithotrophs are organisms that feed on _______ and were discovered by _______.

Inorganic material; Sergei Winogradsky

Which of the following statements about the prokaryotic chromosome is true?

It has a single origin of replication, and the DNA is replicated bidirectionally.

How does the cell membrane affect osmolarity?

It is semipermeable, allowing water molecules to move across while tending to keep solutes in (or out).

What is the role of the first structural gene (lacZ) in the lac operon? Select all that apply.

It isomerizes lactose into allolactose. It breaks down lactose into glucose and galactose.

In E. coli, why is sigma-‐70 considered the "housekeeping" sigma factor?

It keeps essential genes and pathways operating.

What is the advantage of incorporating a positive regulator like CRP into an inducible system like the lac operon?

It provides another layer of control that builds in regulatory contingencies for alternative carbon sources.

What is the advantage of using both N1 and N2 primers (in parallel) for detection of SARS-CoV-2 in clinical samples?

It reduces the rate of "false negative" test reports. It reduces the rate of "false positive" test reports.

What would most likely happen to a periplasmic protein in the general secretion pathway if the gene sequence is modified and the N-terminal sequence is significantly shortened?

It will be defective in binding SecB. It will not be cleaved by LepB.

Jerry, a flight attendant for a major airline, had not been feeling well. His supervisor suggested that he get tested for COVID-19. The test involved a nasopharyngeal swab administered by a nurse practitioner. Three days later he was informed the test was positive. What does this result mean?

Jerry has an active SARS-CoV-2 infection.

Which of the following is a unique characteristic of viruses that distinguishes them from the other major groups of microorganisms?

Lack of cell structure

Which of these two probiotic microbes have been used to treat intestinal distress in children?

Lactobacillus and Bifidobacterium

Which of the following describes media and conditions that will be selective for nitrogen-fixing organisms?

Media lack any nitrogen-containing compounds, but N2 is present in the atmosphere.

Match each of the following scientists with his or her major contribution to microbiology.

Nightingale: statistically quantified the impact of infectious disease on human populations Hooke: the first to record observations of microbes through simple microscopes Spallanzani: showed that microbes arise from preexisting microbes and that heat sterilization can prevent microbial growth Pasteur: discovered the microbial basis of fermentation and showed that providing oxygen does not enable spontaneous generation Tyndall: showed that repeated cycles of heat were necessary to eliminate spores formed by certain kinds of bacteria

Vascular plants absorb the majority of their essential nitrogen from soil in the form of

Nitrate Ammonium

One form of genome organization in a bacterial cell is the compartmentalization of chromosomes and plasmids. When bacterial chromosomes and plasmids are fluorescently labeled in vivo, chromosomes are consistently localized to the___, and plasmids are consistently localized to the __.

Nucleoids; cell poles

In E. coli, the sigma S regulon is important for cellular responses to which of the following?

Nutrient depletion Oxidative stress pH extremes

Cyanobacteria do not rely on other organisms for nutrition, but they do depend on other organisms for waste product removal. Which cyanobacterial waste product can be toxic to them?

Oxygen

Peptidyl transferase catalyzes the movement of the peptide from the tRNA in the _____ to the tRNA in the _____.

P-‐site; A-‐site

It is essential that sister chromosomes avoid the septum formation at the midline of the cell during bacterial cell division in order to prevent septal "guillotining" of chromosomes. Which of the following is not directly involved in the mechanism to prevent septal guillotining of chromosomes?

ParC

Manuel identified a microbe that is responsible for an unexplained respiratory illness in lab mice. He found the culprit in 14 ill mice, and he produced a pure culture of the microbe in the lab. He hasn't yet received permission from the board of ethics to continue his study. Which of Koch's four postulates has Manuel satisficed?

Postulates #1 and #2 only

The cytoplasmic membrane is another cell component that is sensitive to pressure. How does pressure alter cell membranes, and how do barophiles adapt?

Pressure makes cell membranes less fluid. Barophiles adapt by using high levels of polyunsaturated fatty acids.

Prokaryotes vs Eukaryotes

Prokaryotes: Archaea, Bacteria Eukaryotes: Plants, Animals, Protists, Algae, Fungi

Sort the following chromosome characteristics based on whether they describe eukaryotic or prokaryotic chromosomes.

Prokaryotic: Termination zones (ter sites) operons nucleoids Circular or linear chromosomes Eukaryotic: Histones Telomeres nucleus all linear chromosomes

Some bacterial viruses can insert their genome into the chromosome of the host cell. What is the integrated genome called?

Prophage

Which of the following may be present as part of the prokaryotic genome?

Prophage, chromosome, plasmid

Most Gram-‐negative bacteria belong to what phylum?

Proteobacteria

Identify which organisms can be infected by viruses.

Protists Archaea Animals Bacteria Plants Fungi

Which of the following serves as the genetic material of a coronavirus?

RNA

Which key enzyme directly involved in the above process is not explicitly shown in the illustration?

RNA polymerase

The protein _______ is the activator of the SOS response.

RecA

Which of the following statements is true about the rolling-circle mechanisms of plasmid replication?

RepA nicks one strand of the double-stranded DNA plasmid.

Sort the following events according to whether they occur in replicative transposition, nonreplicative transposition, or both:

Replicative: -Donor DNA retains a copy of insertion sequence. -Recombination separates donor and target DNAs. Nonreplicative: -Hairpin structures form on each end of insertion sequence. -Insertion sequence "jumps" into recipient DNA. -Donor DNA loses insertion sequence. Both: -DNA polymerase fills in gaps. -Transposase is required. -Target sequence gets duplicated. DNA ligase seals nicks.

A bacterial species is transferred into a new environment containing many species of novel phage. Predict which defense mechanism will be most protective, initially, against these phage.

Restriction

Studies of bacterial defense mechanisms against bacteriophage infection have yielded important reagents that are used today to manipulate DNA and RNA sequences in the laboratory. Which of the following exemplify these advancements (select all that apply)?

Restriction endonucleases CRISPR-‐Cas9

Which of the following combinations include only macronutrients?

S, O, Mg, Ca, K

Which of the following is a major advantage of single-cell genomics (SCG) over shotgun sequencing?

SCG requires less sample DNA.

How is the small ribosomal unit positioned to allow for translation to start at the proper start codon?

Shine-Dalgarno sequence

How does temperature affect microbial physiology?

Slightly increased temperature speeds up the action of enzymes, thus increasing microbial metabolism.

In what ways do virions resemble living cells?

Some virions possess genes for tRNA. They possess genes that can direct their own replication. Their genomes can be larger than some cellular genomes

Asymptomatic transmission should be suspected when a person contracts COVID-19 following contact with which of the following?

Someone with no signs of illness, but whose coworker tested positive for the virus

Coronaviruses are a family of viruses so named because of the characteristic appearance of their ________ when visualized by scanning electron microscopy.

Spike proteins

The termination of transcription can be caused by which of the following?

Stem-‐loop structure Rho factor

Which of the following is found in the cell wall of a Gram-‐positive bacterium but NOT in that of a Gram-‐negative bacterium?

Teichoic acids

Which of the following is an accurate statement regarding the ACE2 receptor?

The ACE2 receptor is present on a variety of cells and tissues.

In the RT-PCR diagnostic assay for SARS-CoV-2, which of the following would indicate a positive result?

The Ct occurs before the cutoff cycle.

Although Vibrio cholerae is approximately 0.5 µm wide and 1.5 µm in length, filtering water contaminated with Vibrio cholerae through a cloth with 20-µm mesh holes was successful in reducing cholera infections in Bangladesh. Why?

The cloth was able to filter out copepods, which are colonized by Vibrio cholerae.

Which of the following statements applies accurately the italicizedviral term according to its deLinition?

The eukaryote could not eliminate its integrated provirus.

What two conditions must be met to produce a heritable mutation?

The mutation does not get repaired before the cell divides. There is a change in the DNA sequence.

Select the true statement regarding the relationship between genotype and phenotype.

The phenotype reflects only the portion of the genotype that is expressed.

E. coli is a barosensitive organism. How does high pressure affect E. coli ribosomes?

The ribosomes dissociate.

The spike protein of the SARS-CoV-2 virus is important for infection because

The spike protein binds ACE2 on host cells triggering endocytosis

Which of the following statements regarding the phosphotransferase system (PTS) is(are) TRUE?

The system has a modular design that accommodates different substrates. The substrate being transported is altered during passage into the cell.

What would be the effect of water evaporating from a puddle without anything else acting on it?

The water activity would decrease due to an increase in the concentration of dissolved substances.

All of the following describe the unique characteristics of eukaryotic chromosomes, except which statement?

They contain regulatory DNA sequences.

Which of the following directly describes where the name ABC transporters comes from? (It is another name for what the acronym "ABC" means.)

They have nucleotide binding domains.

If halophiles require high environmental concentrations of salt (NaCl), then why do they have such high intracellular concentrations of potassium?

They keep sodium levels low by replacing it with potassium since sodium can be used for symport with other solutes.

How do photosynthetic marine microbes affect Earth's atmosphere?

They produce 50% of Earth's oxygen gas.

How would removing the operator region from the E. coli tryptophan operon affect transcription of the trp genes?

Transcription of the operon would occur even if tryptophan were abundant.

Consider the descriptions of genetic exchange methods below and match each description to the proper type of exchange.

Transformation: This method would be affected by DNase, an enzyme that can degrade naked DNA that is unprotected. Conjugation: This method of DNA exchange cannot occur using the recipient cells mixed with cell-free extract only. Transduction: This method can occur with cell-free extract only and is not affected by DNase.

What are the basic parts of an insertion sequence?

Transposase coding region and two flanking inverted repeats

by characterizing the function of a second messenger that is involved in interspecies communication. If you want to continue your work in this field, in which of the following molecules would you be least interested?

Tryptophan

What key feature of marine viruses drives biodiversity in the oceans?

Viruses have very limited host ranges.

All cells are made up of water and essential ions as well as small and large organic molecules. Order the following components in E. coli during balanced exponential growth from greatest to least in terms of percentage of total cellular weight.

Water--> Protein --> Nucleic acid --> Lipids --> Inorganic Ions

Which criteria of Koch's postulates would not necessarily be met when trying to link a particular bacterium to a latent infection, such as tuberculosis or Lyme disease?

When the microbe is introduced into a healthy, susceptible host, the same disease occurs. The microbe is found in all cases of the disease but is absent from healthy individuals.

Do scientists expect that vaccination against SARS-CoV-2 will produce long-lasting protection?

Yes, because it mutates more slowly than other RNA viruses (e.g., influenza).

A pure culture refers to

a culture that contains a single type or strain of microorganism.

Which of the following describes a possible type of viral-vector vaccine for SARS-CoV-2?

a recombinant "harmless" virus (e.g., adenovirus) that carries genes for coronavirus proteins

What is an intein?

a self-splicing protein

It has been shown recently that many bacteria export bits of cytoplasm in membrane vesicles. What functions do these vesicles serve?

a)Attractors of partner heterotrophs b)Decoys for bacteriophages c)Vehicles for DNA transfer d)Choices A and B are true. e)Choices A, B, and C are true.

Which of the following scenarios would cause a peritrichously flagellated bacterium (like E. coli) to swim in a forward motion?

all flagella turning counterclockwise

Which best describes a genome?

all the genetic information possessed by a cell or virus

Attenuation is a common regulatory strategy used to control the transcription of operons that code for

amino acid biosynthesis.

A Gram-negative cell envelope contains

an inner cell membrane, thin peptidoglycan layer, and outer membrane.

Tetracycline is an antibiotic that works by binding to the 30S subunit of bacterial ribosomes, thus inhibiting protein synthesis. This drug is able to cross the cell membrane because

as a weak base, it can cross the membrane in its uncharged form.

Permeases, periplasmic nutrient-binding proteins, and membrane-spanning pores (porins) all function to

assist in the uptake of molecules too big or polar to diffuse across lipid bilayers.

Suppose you have isolated a compound that alters the quorum signal of Pseudomonas aeruginosa, such that it cannot interact with its normal receptor. Bacterial cells targeted by such a disrupter would most likely

be similar to free-living cells in their sensitivity to antibiotics.

Why is ATP hydrolysis required for these transporters to operate properly?

because it causes a conformational change to open the channel to the other side

For the mismatch repair system to work correctly, newly replicated DNA must

become methylated before the subsequent round of replication. remain unmethylated long enough for mismatches to be repaired.

Concerning the RNA polymerase holoenzyme, which of the following are the core subunits or factors needed for transcription?

beta subunit beta-prime subunit alpha subunits

Early microbial ecologists knew that hydrogen gas is oxidized in soil and that ammonia is oxidized in sewage. How did these scientists determine that microbes are responsible for these ecological reactions?

by applying heat and antimicrobial treatment to sewage samples and observing that nitrate was no longer formed

Increased synthesis of ___ is a direct result of decreasing glucose levels.

cAMP

Bacteria exposed to quinolone-type antibiotics rapidly become unable to

carry out normal gene expression. replicate their DNA. condense and package their chromosomes.

Which of the following elements must be present for attenuation of the trp operon to occur? Select all that apply.

charged tRNATrp RNA polymerase Ribosomes

Cells of a normally rod-shaped bacterium (e.g., Bacillus subtilis) that have completely lost the ability to produce the MreB protein would mostly likely be

coccoid-shaped.

The amino acid tryptophan functions as a(n) ____ in the control circuit of the trp operon.

corepressor

Base excision repair is particularly useful for removing bases from DNA that have spontaneously

deaminated.

All of the following would represent good research applications for cell fractionation except

determining whether a bacterium can metabolize certain sugars

MacConkey agar is an example of a medium that is which of the following?

differential based on ability to ferment lactose, selective for Gram-negative bacteria

What is the primary function of ruminant microorganisms?

digestion of cellulose to organic acids

Which of the following would have the greatest effect on cell function due to changes in pH?

disrupting protein secondary structure, thus decreasing enzyme activity

When could virions (such as T4 phage particles) be detected within an E. coli cell?

during the end of the lytic cycle

A single base-pair mutation occurs in a promoter sequence of a gene. As a result of the mutation, what are the possible effects on the transcription level of the gene?

elimination reduction increase

During base excision repair, a specific glycosylase catalyses

formation of an AP site.

Which of the following requires a protein?

formation of hydrogen peroxide from a superoxide radical

The invention of the ultracentrifuge led to rapid advances in cell biology by allowing scientists to do which of the following?

fractionate subcellular parts

The early stages of genome reduction in bacteria are normally characterized by the proliferation of pseudogenes. These most likely arise as a result of

frameshift and nonsense mutations.

Chaperones are proteins that

help other proteins fold properly.

Which of the following pairs make up a classic two-component signal transduction system?

histidine kinase and response regulator

Genes that share a common ancestry are broadly referred to as ___ . They are further classified as ___ if they exist within the same species but have distinct functions, while ____ usually have similar functions but are found within different species.

homologs; paralogs; orthologs

What accounts for the rapid increase in Aliivibrio fischeri autoinducer after the threshold concentration has been reached?

induction of luxI by LuxR

Tetracycline binding is most similar to that of which of the following?

initiation factor 1 (IF1)

The presence of hydroxyl radicals indicates that the cell likely has which of the following?

iron

Spontaneous generation is the notion that

living organisms arise from nonliving matter.

Compared to a random walk, a biased random walk has ______________ runs and a _____________ frequency of tumbling.

longer / decreased

Which of the following represents an early sign or symptom of COVID-19 that can help distinguish it from other respiratory tract infections?

loss of taste and smell

Which of the following is not a mechanism by which plasmids ensure their inheritance and maintenance during cell division?

low-copy-number plasmids

The temperate phage lambda can undergo two life cycles depending on the environmental cues. During which cycle does phage lambda form a prophage?

lysogeny

Immediately upon release into the host cell cytoplasm, the SARS-CoV-2 genome functions as which of the following?

mRNA

A mutation occurs upstream of Gene A in the region encoding the ribosome binding site. Predict how this mutation will impact the levels of mRNA and protein produced for Gene A.

mRNA levels will remain constant, protein will decrease.

A raindrop of almost pure water lands on a microbe. Which housekeeping strategy, activated by osmotic pressure, is used by microbes to reduce their internal solute concentration by letting solutes out?

mechanosensitive channels

Biofilms preferentially form in __________ environments with __________ levels of nutrients.

moist / high

What is the diagnostic test for SARS-CoV-2 designed to detect?

nucleocapsid RNA

The major factor limiting bacterial growth in nature is

nutrients.

Bacterial replication begins at a single, defined DNA sequence known as

oriC

Antibiotics that weaken the peptidoglycan cell wall make a bacterium more prone to

osmotic lysis

Certain aquatic bacteria use magnetosomes to direct them to environments with optimal levels of

oxygen

For a Gram-negative bacterium such Escherichia coli, the four major destinations for extracytoplasmic proteins (proteins not in the cytoplasm) are the plasma membrane, extracellular spaces, the outer membrane, and the

periplasm

In the marine environment, which types of organisms form the base of the food chain?

photoautotrophic microorganisms

Upon reorienting after a tumble, an E. coli cell

points itself in a random direction.

Identify the function(s) of the viral capsid.

protects the viral genome determines the shape of the virion

Which of the following modifications would likely cause constitutive expression of a gene that is normally regulated by an activator protein?

replacing the promoter with the consensus sequence for RpoD σ70

Unlike primary chromosomes, secondary chromosomes in bacteria have which quality?

replication using plasmid-like molecular mechanisms

Transcription is prevented by _______ and stimulated by _______.

repressors; activators

Bacterial flagella undergo ________ motion, and are driven by ________.

rotatory; proton motive force

Why might regulation by sRNA be considered more energetically efficient than regulation by repressors?

sRNAs do not need to be translated.

Many bacteria adapt to adverse environmental conditions by modifying the composition of their cell membranes. For example, the membranes of bacteria subjected to heat stress often contain high levels of which of these compounds?

saturated fatty acids

In bacteria, a partially diploid strain may result from

specialized transduction. Acquisition of an F' factor.

Which component of SARS-CoV-2 is believed to be the most promising target for vaccine development?

spike protein

The hopanoids in bacteria are equivalent to the ______ in eukaryotes.

sterols

Association of RecA with an incoming piece of foreign DNA is required for a cell to do which of the following?

swap the incoming DNA with a homologous region on the chromosome

V. cholerae is capable of transformation, which means it can do what?

take up naked DNA

Which of the following is the best example of an extremophile?

the hyperthermophile bacteria Methanopyrus kandleri 1st attempt

Suppose a bacterium was exposed to a chemical that poisoned its cytochrome oxidase. Which of the following transport processes would be affected first?

the lactose symporter (LacY)

The "coding region" of a gene corresponds to which?

the nucleotides that specify the amino acid sequence of a protein

Which of the following techniques would be best to use to study extremophiles that cannot be cultured in normal laboratory conditions?

the polymerase chain reaction to amplify the DNA to have enough for further analysis

For what purpose does the bobtail squid (Euprymna scolopes) use the light produced by its symbiotic A. fischeri?

to avoid predation

The sigma factor is directly required for

transcription initiation.

Gene transfer from one bacterium to another by means of a bacteriophage is called _______, whereas _______ involves the transfer of DNA following cell-‐to-‐cell contact.

transduction; conjugation

Which mechanism of gene transfer among microbes was elucidated by the team of Avery, MacLeod, and McCarty?

transformation

Active transport is required for bacterial cells to

transport solutes against their concentration gradient

A mutation changes the codon UAC to UAA. This is an example of

transversion and nonsense mutations.

During methyl mismatch repair the ___________ strand is cleaved because it is the ______________ strand.

unmethylated, newly synthesized

What is the mechanism by which progeny SARS-CoV-2 virions exit an infected host cell?

vesicle fusion with the plasma membrane

There are only about 40 different tRNAs in a cell even though 61 codons code for amino acids. This discrepancy can be attributed to the fact that the first nucleotide in the anticodon can base-pair with more than one nucleotide in the codon. This phenomenon is known as __________ and is, in part, due to __________ and the presence of __________ at this position in some tRNA molecules.

wobble; the curvature of the anticodon loop; inosine