Microbiology lecture exam 2 Flashcards by Alicia 1

A capnophile is a microorganism that thrives in conditions of high

carbon dioxide levels.

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The members of a bacterial population known as persister cells may

not be actively growing

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Antimicrobial agents that damage nucleic acids also affect

protein synthesis

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Hydrogen peroxide is an effective

disinfecting and sterilizing agent

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A cell that uses an organic carbon source and obtains energy from light would be called a

photoheterotroph

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Codons are recognized during

translation.

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The tetracyclines interfere with

protein synthesis

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Two bacterial strains have the same genes for metabolizing a carbohydrate, but one is wild-type for a regulatory inducer while the other does not produce the inducer. Which of the following statements is CORRECT with regard to the metabolism of the bacteria?

The two bacterial strains have different phenotypes.

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Mutagens are useful in biotechnology research for

producing organisms with altered phenotypes.

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Which of the following is common to both Sanger sequencing and next-generation sequencing?

chain terminating nucleotides

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If a researcher used Escherichia coli DNA polymerase instead of Thermus aquaticus DNA polymerase in the PCR procedure, what would be the result?

DNA replication would stop after one cycle.

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Why are endospores used to measure the effectiveness of autoclave sterilization?

Correct Answer

Endospores are very hard to kill.

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Heat shock” is an effective means of

introducing DNA into bacteria.

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In the process of ________, microbes detect the presence and density of other microbes and modify their metabolic activity in response.

quorum sensing

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Which of the following items is NOT a part of the name of a restriction enzyme?

the Gram reaction of the source bacterium

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The carotenoid pigments of some phototrophs interact with ________ to reduce its toxicity.

singlet oxygen (1O2)

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Who proposed the concept of chemotherapy, especially antimicrobials?

Paul Ehrlich

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Which of the following is used for microbial control in fresh fruits and vegetables?

gamma rays

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An epidemiologist is investigating a new disease and observes what appear to be bacteria inside tissue cells in clinical samples from victims. The scientist wants to try to isolate the bacteria in the lab. What culture conditions are most likely to be successful?

inoculation of cell cultures

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Disinfectants that damage membranes include

both alcohol and phenolics.

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The cooperative activity of drugs such as beta-lactam antibiotics and clavulanic acid, a β-lactamase inhibitor, is known as

synergism.

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Antimicrobials known as “attachment antagonists” are particularly useful for preventing

virus infection.

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Subunit vaccines are safer than traditional vaccines because they

are acellular and do not pose a risk for causing the disease.

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You notice a sign in a public restroom that states “Sanitized for your safety.” This means

methods of disinfection that meet minimum standards of microbial removal have been used.

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Which of the following microbes produces a protein that kills a variety of insect pests?

Bacillus thuringiensis

A polypeptide in a wild type microbe contains the sequence Leu-Pro-Tyr-Ser-Pro. A phenotypic variant of the species has the peptide sequence Leu-Pro-Cys-Ser-Pro. This is an example of a(n) ________ mutation.

missense

MacConkey agar plates represent ________ medium.

both a differential and a selective

The process indicated by the arrow in Figure 7.1 represents Correct Answer

LAGGING STRAND SYNTHESIS -look at picture

An aquatic microbe that can grow only near the surface of the water is probably which of the following?

a phototroph

Which of the following organisms would be most likely to contaminate a jar of pickles?

an acidophile

Organisms that can grow with or without oxygen present are

either facultative anaerobes or aerotolerant anaerobes.

An axenic culture is one which

contains only a pure culture.

During elongation, a charged t-RNA first enters the ribosomal ________ site and then moves into the ________ site.

A; P

Which of the following is an effect of an antimicrobial that blocks tubulin polymerization?

Preventing mitosis in eukaryotes.

The antimicrobial polymyxin

disrupts cytoplasmic membranes.

Seventy percent alcohol is effective against

enveloped viruses.

A chemical agent that dissolves lipids can damage

cells and enveloped viruses.

Creating conditions in the laboratory that promote the growth of some microbes while inhibiting the growth of others is called

enrichment culturing.

Which of the following is a product of recombinant DNA technology?

microbes that produce vitamins, insulin and vaccines

Which of the following microbes has been genetically engineered to contain a protein that helps protect crops from freezing?

Pseudomonas

A scientist develops a new medication that is a protein compound and that must be administered by injection. Which of the following would be the most effective and safest means of preparing a sterile solution of the new medication?

filtration

Microaerophiles are microbes that grow best at low

oxygen levels.

Methicillin is an example of the beta-lactam class of drugs that

inhibits cell wall synthesis.

Alcohols are used for

both antisepsis and disinfection.

Which of the following describes flash pasteurization?

heating at 72°C for 15 seconds

Altering an organism’s phenotype by ________ is a technique for determining the function of a gene.

gene knockout

The enzyme reverse transcriptase

synthesizes DNA from an RNA template.

Probes used for detecting genetic sequences are frequently composed of

synthetic nucleic acids and labeled conjugates, such as fluorescent dyes.

In gel electrophoresis, DNA molecules move toward the ________ electrode because they have an overall ________ charge.

positive; negative

AZT and Valaciclovir are antiviral nucleoside analogs that interfere with

nucleic acid synthesis.

It is inappropriate to prescribe antibacterial agents to treat colds or flu because

these diseases are caused by viruses.

Washing dishes in the dishwasher with detergent and hot water is a ________ process.

degerming and disinfecting

Infection of the ________ would be the hardest to treat with antimicrobial drugs.

brain

The therapeutic window of an antimicrobial is the

range of concentrations at which the antimicrobial is both effective and non-toxic.

An antimicrobial is described as preventing alanine-alanine bridge formation. This means it

prevents cell wall synthesis in bacteria.

If all the following DNA fragments were analyzed on an electrophoresis gel, which one would migrate farthest from the negative electrode?

250 base pairs

Which of the following restriction enzyme sites would produce blunt-ended fragments? (The arrow represents the cutting site of the enzyme.)

CCC↓GGG

Rates of cell production and cell death are approximately equal during the ________ phase of growth.

stationary

If the codon AAA is changed to AAG, it still codes for the amino acid lysine; this is an example of a

silent mutation.

Methods of microbial control called ________ arrest the growth of microbes.

germistatic

The process of ________ requires the activity of DNA ligase.

DNA replication

The effects of a transposition event are equivalent to a(n)

frameshift mutation.

A procedure using both reverse transcriptase and real time PCR can be used to

both determine the number of copies of an RNA sequence in a sample and produce fragments for cDNA cloning.

Ultra-high-temperature sterilization effectively

removes all microbes that cause diseases or spoilage.

Quaternary ammonium compounds are disinfectants effective against

enveloped viruses.

In conjugation, F+ cells

contain an F plasmid.

Which of the following would be used to sterilize a mattress?

ethylene oxide

A microbe that grows only at the bottom of a tube of thioglycollate medium is probably a(n)

obligate anaerobe.

Which of the following processes is involved in the "central dogma" of genetics?

transcription and translation

Formalin (37% formaldehyde) is used for

both disinfection and sterilization.

In the CRISPR system, the targeted DNA sequence is

in the spacer of a CRISPR region.

Synthesis of cDNA requires the use of

reverse transcriptase.

Nitrogen is a growth-limiting nutrient for many organisms because

only a few microbes can extract it from the atmosphere, but all organisms require it for amino acid and nucleotide synthesis.

Which of the following drugs inhibits nucleic acid synthesis specifically in most bacteria?

fluoroquinolones

The process of ________ is described as semiconservative.

DNA replication

Which of the following can result when antibiotic therapy disrupts the normal microbiota?

both pseudomembranous colitis and thrush

Which of the following is bacteriostatic?

freezing below 0°C

The mechanism of action of the antibiotic vancomycin is

inhibition of cell wall synthesis.

Which of the following is NOT a characteristic of both DNA and RNA polymerases?

A primer is required for initiation.

Amino acids are delivered in their appropriate order by

tRNAs.

Which of the following steps in the folic acid synthesis pathway is specifically inhibited by sulfonamides?

the conversion of PABA to dihydrofolic acid

Which of the following DNA repair processes is most likely to introduce mutations into the repaired DNA?

SOS repair

Which of the following groups of drugs can become incorporated into the bones and teeth of a fetus?

tetracyclines

The events of ________ are initiated at sequences called origins.

DNA replication

A microbiologist inoculates a flask of broth to a concentration of 100 bacterial cells per ml. The generation time of the species is 1 hour, and there is no lag phase. How long will it be before the culture contains more than 6,000 cells per ml?

6 hours

Which of the following is generally NOT considered an ethical issue regarding recombinant DNA technology

answering basic research questions

Which of the following is a sterilizing agent?

peracetic acid and hydrogen peroxide

The generation time of bacterial cells is shortest during the ________ phase.

log

An antimicrobial that inhibits bacterial cell wall synthesis will result in which of the following?

Bacterial cells become more susceptible to osmotic pressure.

Prokaryotic operons typically include a(n) ________ and a(n) ________ with multiple genes.

operator; promoter

Which of the following is NOT a characteristic of Okazaki fragments

They are longer in eukaryotic cells.

The process of filtration can be a(n)

sterilizing method.

Genetic elements known as promoters are initiation points in the process of

transcription.

Which of the following is characteristic of prokaryotic genomes but not eukaryotic genomes?

circular chromosomes

The use of salt and sugar in preserving various types of foods is an application of which of the following concepts?

osmotic pressure

The natural role of restriction enzymes in bacteria is to

protect the cell from invading phages.

Some bacteria are resistant to erythromycin as a result of mutation of their ribosomal RNA. What type of resistance does this represent?

alteration of the target of the drug

Blood agar plates are an example of ________ medium.

differential

Ted heats some food just to boiling, and stores some of it immediately in a container which he places in the refrigerator. A week later he takes the food out and finds it has spoiled. The microbes that spoiled the food are probably ________ organisms.

thermoduric

Which of the following statements concerning transcription in bacteria is FALSE?

Different RNA polymerases are required for synthesis of mRNA, rRNA, and tRNA.