Chapter 7

Based on the animation, what is transferred during bacterial conjugation? A conjugation pilus A bacterial chromosome RNA A bacterial plasmid

A bacterial plasmid

Okazaki fragments are formed because DNA replication A. is performed by different versions of DNA polymerase in different cells B. is discontinuous on the lagging strand C. involves proofreading D. is semiconservative

B. is discontinuous on the lagging strand

Which of the following might result in a frameshift mutation? Benzopyrene Nitrous acid 5-bromouracil

Benzopyrene

Which of the following enzymes is responsible for "unzipping" a DNA molecule in preparation for its replication? DNA polymerase DNA ligase primase DNA helicase

DNA helicase

Which of the following enzymes is responsible for "unzipping" a DNA molecule in preparation for its replication? primase DNA polymerase DNA helicase DNA ligase

DNA helicase

What characteristic of DNA allows two connected DNA polymerases to synthesize both the leading and lagging strands? DNA has a helical shape. DNA is double-stranded. DNA is flexible. DNA is antiparallel.

DNA is flexible.

Which enzyme joins the gaps between synthesized DNA fragments of the lagging strand? DNA ligase DNA polymerase RNAse Primase

DNA ligase

Which of the following is capable of conjugation? F+ and Hfr cells bacteriophages F+ cells F- cells

F+ and Hfr cells

What was the significance of Frederick Griffith's experiments with Streptococcus pneumoniae? He showed that the DNA from strain R cells could transform strain S cells. He showed that the DNA from strain S cells could transform strain R cells. He showed that strain R and strain S cells could be killed by heat. He showed that strain R cells could easily take up capsules released by dead S cells.

He showed that the DNA from strain S cells could transform strain R cells.

Which of the following is capable of conjugation and typically produces a recombinant cell incapable of conjugation? Bacteriophages F+ cells Hfr cells F− cells

Hfr cells

Which of these is NOT a difference between eukaryotic and bacterial gene expression? Bacteria may have genes organized and regulated within operons, while eukaryotes lack operons. Initiation of translation in bacteria occurs when the ribosomal subunit binds to the 5' guanine cap, while in eukaryotes it binds to a specific nucleotide sequence. Bacteria have 70S ribosomes, while eukaryotes have 80S ribosomes in their cytoplasm. Eukaryotic RNA is modified prior to translation, whereas bacterial RNA is not.

Initiation of translation in bacteria occurs when the ribosomal subunit binds to the 5' guanine cap, while in eukaryotes it binds to a specific nucleotide sequence.

According to the animation, which of the following makes mRNA from the information stored in a DNA template? a. tRNA b. Ribosomes c. RNA polymerase d. DNA polymerase

RNA polymerase

How many codons code for the amino acid arginine? One Four Six Three

Six

What nucleotides would DNA polymerase add if it encountered the nucleotide sequence: ATTGC? GCAAT TAACG CGTTA ATTGC

TAACG

In a repressible operon, which of the following must occur to enable gene expression? The corepressor must bind to the repressor. The repressor must bind to the operator. The inducer must bind to the repressor. The corepressor is absent.

The corepressor is absent.

In a repressible operon, which of the following must occur to enable gene expression? The corepressor must bind to the repressor. The corepressor must be absent. The inducer must bind to the repressor. The repressor must bind to the operator.

The corepressor must be absent.

Which of the following must occur to enable the transcription of genes in the lactose operon? The inducer must bind to the repressor. The inducer must bind the operator. The repressor must bind to the operator. The inducer must bind RNA polymerase.

The inducer must bind to the repressor.

According to the animation, where on the DNA strand does a repressor bind? The operator The inducer The structural genes The promoter

The operator

What is a nosocomial infection? a. This is a MRSA infection. b. This is an infection acquired by swimming in contaminated lake water. c. This is a hospital-acquired infection. d. This is a nutritional deficiency aggravated by hospital food that is served cold.

This is a hospital-acquired infection.

Which of the following amino acids is coded by only one codon? His Glu Phe Tyr Trp

Trp

Bacterial conjugation is often referred to as bacterial sex. Why is this term inaccurate? a. Conjugation does not result in the formation of new offspring. b. Bacteria are neither male nor female. c. Sex is a phenomenon only seen in animals. d. It does not require two cells to occur.

a. Conjugation does not result in the formation of new offspring.

RNA that has hydrogen bonded to itself forms a a. stem loop. b. termination protein. c. terminator sequence. d. promoter sequence.

a. stem loop.

Which operons are always transcribed unless deactivated? a. Inducible operons b. Repressible operons c. Inducible and repressible operons

b. Repressible operons

Which of the following statements is NOT accurate about microbial DNA? a. Most bacteria and archaea have circular DNA in the cytoplasm, while most eukaryotes have linear DNA in the nucleus. b. The chromosomes and plasmids in bacteria, archaea, and eukaryotes contain double-stranded DNA. c. All of the DNA in eukaryotic cells is contained within a nucleus. d. Archaea and eukaryotes have histone proteins associated with their DNA, while bacteria do not have histones.

c. All of the DNA in eukaryotic cells is contained within a nucleus.

What term is used to describe bacterial cells that can naturally take up DNA from their environment? auxotrophs Hfr cells electroporated cells competent cells

competent cells

A mutation that causes production of a defective pilus in a bacterium will prevent transduction translation conjugation transformation

conjugation

A mutation that causes production of a defective pilus in a bacterium will prevent __________. transformation translation conjugation transduction

conjugation

Which of the following is NOT used by bacteria to acquire new genetic material? crossing over transformation transduction conjugation

crossing over

According to the animation, how do the repressor proteins block the transcription of the structural genes? a. It binds to the repressor when deactivated. b. It binds to the promoter when activated. c. It binds to the repressor gene when activated. d. It binds to the operator when activated. e. It binds to the repressor gene when deactivated. f. It binds to the promoter when deactivated.

d. It binds to the operator when activated.

As shown in the animation, the start codon also codes for which amino acid? a. Alanine b. Proline c. Glycine d. Methionine e. Serine

d. Methionine

Transcription produces which of the following? a. mRNA b. rRNA c. tRNA d. mRNA and tRNA e. mRNA and rRNA f. mRNA, tRNA, and rRNA are all produced by transcription.

f. mRNA, tRNA, and rRNA are all produced by transcription.

A new chemotherapeutic agent is developed that alters the structure of all thymines in DNA. These thymines are then misread during the production of mRNA. Which of the following could NOT result from this type of mutation? frameshift mutation silent mutation missense mutation nonsense mutation

frameshift mutation

Insertions and deletions usually lead to which of the following types of mutations? silent mutations base-substitution mutations frameshift mutations pyrimidine dimers

frameshift mutations

The Ames test involves mutants of Salmonella that __________ the ability to make histidine in the __________ of a suspected mutagenic chemical. gain; presence lose; absence gain; absence lose; presence

gain; presence

Okazaki fragments are formed because DNA replication __________. involves proofreading is semiconservative is performed by different versions of DNA polymerase in different cells is discontinuous on the lagging strand

is discontinuous on the lagging strand

What does MDR mean? minimal drug resistance multi-directional radioactivity map directed route multi-drug-resistant

multi-drug-resistant

Which of the following types of mutations creates a stop codon where one did not exist before? frameshift mutation nonsense mutation missense mutation silent mutation missense mutation silent mutation

nonsense mutation

Which of the following types of mutations creates a stop codon where one did not exist before? silent mutation nonsense mutation frameshift mutation missense mutation

nonsense mutation

While studying protein synthesis in the lab, you experimentally induce a mutation in a bacterium's DNA. You assess the proteins in the mutated bacterium and find that one of them is significantly shorter than its wild-type counterpart. Based on this information, what type of mutation did you induce? deletion mutation nonsense mutation missense mutation silent mutation

nonsense mutation

Which of the following is NOT involved in the process of translation initiation? tRNAfMet mRNA ribosomal subunits release factors

release factors

Which of the following regions of a ribosome holds the growing polypeptide? the E site the Z site the P site the A site

the P site

The process of copying DNA genetic information into the form of RNA is called transduction transformation translation transcription

transcription

Bacteriophages are important for which of the following processes? transcription transformation transduction translation

transduction

Which operons are never transcribed unless activated? a. Inducible operons b. Repressible operons c. Inducible and repressible operons

a. Inducible operons

When is the repressor protein transcribed? a. It is always transcribed. b. Only in the absence of tryptophan c. Only in the presence of tryptophan

a. It is always transcribed.

Which of the following are terms associated with Okazaki fragments? a. Lagging strand, DNA ligase, and discontinuous b. Lagging strand c. Discontinuous d. DNA ligase

a. Lagging strand, DNA ligase, and discontinuous

Which of the following repair mechanism(s) does not involve DNA polymerase? a. Light-repair mechanism b. Excision-repair mechanism c. Mismatch-repair mechanism

a. Light-repair mechanism

How does an F+ cell differ from an Hfr cell? a. F+ cells have no plasmids. b. Hfr strains have the F plasmid integrated into the chromosome. c. Hfr cells cannot perform conjugation. d. Hfr strains can no longer reproduce

b. Hfr strains have the F plasmid integrated into the chromosome.

Which of the following genetic elements is transcribed into a single mRNA? The structural genes The operator The promoter The inducer The repressor

The structural genes

A silent mutation is so named because __________. a. it has no effect on the overall amino acid sequence b. it causes a frameshift, thus altering protein structure c. it results in a premature termination of the amino acid sequence d. it results from the deletion of DNA, thus silencing the gene

a. it has no effect on the overall amino acid sequence

RNA polymerase is guided by the a. template strand of DNA. b. RNA strand. c. coding strand of DNA.

a. template strand of DNA.

Which of the following repair enzymes cannot repair thymine dimers? a. Excision-repair enzymes b. Mismatch-repair enzymes c. Light-repair enzymes

b. Mismatch-repair enzymes

How can specialized transduction contribute to the transfer of antibiotic resistance genes in a bacterial population? a. The phage causes the destruction of any antibiotic present during the specialized transduction process. b. The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA. c. The phage lyses the bacterium and releases resistance genes into the local environment, which can then be taken up by recipient cells.

b. The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA.

During elongation, how is the RNA synthesized? a. Left to right b. Right to left c. 5' to 3' d. 3' to 5'

c. 5' to 3'

Which of the following statements is NOT accurate about microbial genomes? a. Archaea and eukaryotes have histone proteins associated with their DNA, while bacteria do not have histones. b. Most bacteria and archaea have circular DNA in the cytoplasm, while most eukaryotes have linear DNA in the nucleus. c. All of the DNA in eukaryotic cells is contained within a nucleus. d. The chromosomes and plasmids in bacteria, archaea, and eukaryotes contain double-stranded DNA.

c. All of the DNA in eukaryotic cells is contained within a nucleus.

Ribosomes contain which of the following? a, mRNA, tRNA, and rRNA are all found as part of the ribosome. b. mRNA c. rRNA d. tRNA

c. rRNA

Why must primase be used before DNA polymerase when replicating DNA? a. Primase unwinds the DNA double helix. b. Primase removes RNA primers, allowing DNA polymerase begin synthesis. c. Primase stabilizes the single-stranded DNA. d. Primase provides an RNA primer with a 3' end on which DNA polymerase can act.

d. Primase provides an RNA primer with a 3' end on which DNA polymerase can act.

What characteristic of the S strain allows it to evade the immune system of the mice? a. They are resistant to heat. b. They are genetically engineered to be resistant to killing. c. They are naturally competent. d. The cells have a capsule.

d. The cells have a capsule.

Which statement about conjugation is false? a. Conjugation is a process of bacterial reproduction. b. E. coli is the model for bacterial conjugation. c. After conjugation, each cell involved has a copy of the shared DNA.

a. Conjugation is a process of bacterial reproduction.

How would one increase the concentration of a particular polypeptide in a cell? a. Increase the level of transcription b. Increase the amount of DNA c. Increase the concentration of promoters

a. Increase the level of transcription

What would happen if the mRNA codon that coded for Cys was mutated in the third position from a U to an A? a. The amino acid Cys would still be coded. b. A stop codon would be introduced prematurely. c. The codon would now code for Trp instead of Cys.

b. A stop codon would be introduced prematurely.

With which genetic region does the repressor protein interact? a. lacZ b. The regulatory gene c. The operator region d. lacY e. The promoter region

c. The operator region

Thymine dimers result from a. nucleoside analogs. b. mistakes by DNA polymerase. c. ionizing radiation. d. nonionizing radiation.

d. nonionizing radiation.

Which of the following characteristics of a chromosome would identify it as a prokaryotic chromosome rather than a eukaryotic chromosome? It contains double-stranded DNA. It contains histones. It contains A, C, G, and T. It is a circular molecule.

It is a circular molecule.

Why does conjugation between an Hfr strain and an F- strain not result in two Hfr strains? a. Conjugation is typically disrupted before the fertility factor can be transferred. b. Hfr strains lack fertility factor. c. The transferred genes typically recombine with the recipient chromosome. d. The cell membranes between the two strands never fuse together.

a. Conjugation is typically disrupted before the fertility factor can be transferred.

How is generalized transduction different from specialized transduction? a. Generalized transduction is initiated during lytic cycle of a virulent bacteriophage; specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage. b. Specialized transduction uses animal viruses instead of bacteriophage. c. Generalized transduction is initiated by a lysogenic bacteriophage; specialized transduction is initiated by a lytic phage. d. Only one specific host gene is transferred in both specialized transduction and generalized transduction.

a. Generalized transduction is initiated during lytic cycle of a virulent bacteriophage; specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage.

Which finding is most surprising from Griffith's experiments? a. S strain cells are isolated from the blood of mice infected with heat-killed S strains and live R strains. b. S strains are able to escape phagocytosis. c. S strain cells kill the mice. d. R strain cells fail to produce a capsule.

a. S strain cells are isolated from the blood of mice infected with heat-killed S strains and live R strains.

What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell? a. The host DNA integrates, with the prophage, into the new recipient chromosome. b. The DNA begins to replicate without integrating into the host chromosome. c. The DNA is chewed up by enzymes found in the recipient cell.

a. The host DNA integrates, with the prophage, into the new recipient chromosome.

Why is light required for photolyases? a. The light provides the energy to break the bonds between the thymine dimers. b. The light helps identify the damaged strands. c. Light excises the section of DNA to be repaired. d. Light is used to activate the DNA polymerase to repair the gap.

a. The light provides the energy to break the bonds between the thymine dimers.

How is DNA methylation used in DNA repair? a. The mismatch-repair enzymes can use a lack of methylation to identify and remove newly synthesized DNA. b. Methyl groups are required to cut DNA. c. Methyl groups activate photolyases in light-repair. d. Methyl groups identify thymine dimers in the DNA.

a. The mismatch-repair enzymes can use a lack of methylation to identify and remove newly synthesized DNA.

According to the animation, to what genetic element does the RNA polymerase bind? a. The promoter b. The repressor mRNA c. The operator d. The repressor protein

a. The promoter

Why is the DNA synthesis of the lagging strand considered discontinuous? a. The synthesis is moving in the opposite direction from the replication fork. b. The lagging strand only requires one primer instead of multiple primers. c. DNA synthesis on the lagging strand occurs 3' to 5' d.The lagging strand only produces single-stranded DNA molecules

a. The synthesis is moving in the opposite direction from the replication fork.

What is unique about transduction compared to normal bacteriophage infection? a. Transduction transfers DNA from the chromosome of one cell to another. b. The bacteriophage does not erupt from an infected cell during transduction. c. The bacteriophage takes fragments of the cell with it during transduction.

a. Transduction transfers DNA from the chromosome of one cell to another.

Mutagens a. increase the likelihood of mutations in DNA. b. come in two basic forms: ionizing and nonionizing radiation. c. are the sole cause of mutations in DNA. d. decrease the likelihood of mutations in DNA.

a. increase the likelihood of mutations in DNA.

A recombinant cell a. is a cell that receives DNA from an outside source and incorporates it into its own. b. donates DNA into a new cell. c. is the result of a cell dividing.

a. is a cell that receives DNA from an outside source and incorporates it into its own.

X rays and gamma rays cause which of the following types of problems in DNA? a. physical breaks in chromosomes b. frameshift mutations c. base-pair substitutions d. pyrimidine dimers

a. physical breaks in chromosomes

A mutation that affects the genotype of the organism but not the phenotype is called a a. silent mutation. b. frameshift mutation. c. nonsense mutation. d. missense mutation.

a. silent mutation.

Which of the following is involved in bringing amino acids to the ribosomes? a. rRNA b. mRNA, tRNA, and rRNA are all involved in transporting amino acids to the ribosomes. c. mRNA d. tRNA

a. tRNA

Plasmids have been found in all of the following types of cells EXCEPT protozoan cells prokaryotic cells fungal cells animal cells

animal cells

GAU codes for isoleucine. tryptophan. serine. proline. aspartic acid.

aspartic acid.

In which direction does DNA polymerase synthesize DNA for the lagging strand? a. It alternates between strands (5' to 3', then 3' to 5'). b. 5' to 3' c. The lagging strand is not synthesized by DNA polymerase. d. 3' to 5'

b. 5' to 3'

Which of the following is a characteristic of an F+ cell? a. Ability to synthesize sex pili b. Ability to synthesize sex pili, presence of a fertility factor, and ability to mate with an F- cell. c. Presence of a fertility factor d. Ability to mate with an F- cell

b. Ability to synthesize sex pili, presence of a fertility factor, and ability to mate with an F- cell.

How do complex transposons differ from simple transposons? a. Complex transposons code for transposase; simple transposons do not. b. Complex transposons code for additional genetic elements, such as antibiotic resistance genes; simple transposons only code for the transposase gene essential for the tranposon itself. d. Complex transposons are found in multiple locations in the target DNA; simple transposons are found only in one location

b. Complex transposons code for additional genetic elements, such as antibiotic resistance genes; simple transposons only code for the transposase gene essential for the tranposon itself.

Which of these is NOT a difference between eukaryotic and bacterial gene expression? a. Bacteria may have genes organized and regulated within operons, while eukaryotes lack operons. b. Initiation of translation in bacteria occurs when the ribosomal subunit binds to the 5' guanine cap, while in eukaryotes it binds to a specific nucleotide sequence. c. Bacteria have 70S ribosomes while eukaryotes have 80S ribosomes in their cytoplasm. d. Eukaryotic mRNA is modified prior to translation, whereas bacterial mRNA is not.

b. Initiation of translation in bacteria occurs when the ribosomal subunit binds to the 5' guanine cap, while in eukaryotes it binds to a specific nucleotide sequence.

Which strand will require more RNA primers to complete synthesis? a. Leading strand b. Lagging strand c. RNA primers are not required for DNA synthesis. d. The leading and lagging strands will require the same amount of RNA primers.

b. Lagging strand

Which DNA strand is synthesized continuously? a. Lagging strand b. Leading strand c. Neither the leading nor the lagging strand is synthesized continuously. d. The leading and lagging strands are both synthesized continuously.

b. Leading strand

How frequently do silent mutations occur? a. One out of every billion mutations b. One out of every three mutations c. Half of all mutations d. One out of every million mutations

b. One out of every three mutations

When the cell is NOT in the presence of tryptophan, a. the repressor proteins bind to the operator. b. RNA polymerase can transcribe mRNA. c. the repressor proteins are active. d. structural genes are not transcribed.

b. RNA polymerase can transcribe mRNA.

How does specialized transduction differ from regular lysogeny? a. The resulting bacteriophage from specialized transduction does not contain any viral DNA. b. The prophage in specialized transduction carries with it pieces of the host chromosomal DNA. c. The resulting bacteriophage from specialized transduction cannot infect a new host cell. d. The prophage is not excised during specialized transduction.

b. The prophage in specialized transduction carries with it pieces of the host chromosomal DNA.

What is the basic function of the lac operon? a. To code for enzymes involved in synthesizing lactose. b. To code for enzymes involved in catabolizing lactose. c. To produce lactose when none is present d. To produce glucose when none is available

b. To code for enzymes involved in catabolizing lactose.

What is the overall function of the trp operon? a. To block RNA polymerase from the structural genes b. To ensure that the cell has a supply of tryptophan at all times c. To always make sure the operator is being bound to repressor proteins d. To control the production of repressor proteins

b. To ensure that the cell has a supply of tryptophan at all times

A nucleotide-altering chemical a. can slip in between stacked bases, causing bulges in the DNA structure. b. can alter nitrogenous bases of DNA, resulting in incorrect base pairing. c. can cause double-stranded breaks in the DNA. d. can be incorporated into the DNA, to cause a mispairing of bases.

b. can alter nitrogenous bases of DNA, resulting in incorrect base pairing.

A transducing phage a. cannot infect new host cells. b. contains fragments of the host chromosome instead of the viral genome. c. has a viral coat made of host proteins. d. is a lysogenic bacteriophage.

b. contains fragments of the host chromosome instead of the viral genome.

A base insertion or deletion in the translated region of the gene may lead to a. missense mutation. b. frameshift mutation. c. silent mutation. d. nonsense mutation.

b. frameshift mutation.

When a transducing phage interacts with a new host cell, a. it will cause the new cell to produce more transducing phage. b. the DNA from the previous host can recombine with the new host chromosome. c. the new host cell will be lysed.

b. the DNA from the previous host can recombine with the new host chromosome.

Which type of transposon would contain a gene for transposase? a. Simple transposons b. Complex transposons c. Both simple and complex transposons d. Neither simple nor complex transposons; the transposase enzyme is coded independently by the cell.

c. Both simple and complex transposons

What benefit does the F- strain receive from mating with an Hfr strain? a. It can now produce sex pili. b. It picks up a fertility factor. c. It acquires new, potentially beneficial genes from the Hfr strain. d. It becomes an F+ cell.

c. It acquires new, potentially beneficial genes from the Hfr strain.

What is considered to be the average natural mutation rate that occurs during DNA replication? a. One in every million nucleotides replicated. b. One in every ten thousand nucleotides replicated. c. One in every billion nucleotides replicated. d. One in every trillion nucleotides replicated.

c. One in every billion nucleotides replicated.

What most likely explains the recovery of live S strain cells from a mouse injected with heat-killed S strain mixed with live R strain cells? a. The R strain cells picked up the capsules from the S strain cells. b. The S strain fused with the R strain, making it resistant. c. The R strain picked up the S strain DNA, enabling it to produce a capsule. d. The S strain was revived by the presence of the host's immune system.

c. The R strain picked up the S strain DNA, enabling it to produce a capsule.

What must occur for bacterial conjugation to take place? a. The cells must transfer RNA. b. Each cell must contain a plasmid. c. The cells must come into contact with each other. d. One of the cells must be E. coli.

c. The cells must come into contact with each other.

What is the initial target of RNA polymerase? a. The terminator region b. The template DNA c. The promoter

c. The promoter

What is the function of the connector proteins? a. They produce the Okazaki fragments. b. They enable one parental DNA strand and one newly synthesized DNA strand to be held together. c. They link the leading strand DNA polymerase and the lagging strand DNA polymerase together. d. They allow DNA synthesis to occur in the 3' to 5' direction.

c. They link the leading strand DNA polymerase and the lagging strand DNA polymerase together.

What is the hallmark of all horizontal gene transfers? a. Transfer of DNA using a virus b. Transfer of DNA from parent to offspring c. Transfer of DNA between organisms of the same generation d. The use of plasmids

c. Transfer of DNA between organisms of the same generation

Why is the tryptophan operon turned off in the presence of tryptophan? a. Tryptophan is not an important amino acid for cells. b. Tryptophan can be used over and over again in the cell. c. Tryptophan binds to and activates the repressor proteins; the repressor proteins, in turn, bind to the operator, preventing transcription.

c. Tryptophan binds to and activates the repressor proteins; the repressor proteins, in turn, bind to the operator, preventing transcription.

A haploid cell has a. only one chromosome b. more than one chromosome c. a single copy of each of its chromosomes d. two copies of each chromosome

c. a single copy of each of its chromosomes

Competent cells are cells that a. have the ability to produce capsules. b. are killed by heat. c. can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination. d. are also considered "rough-strain" based on colony phenotype.

c. can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination.

Which of the following can be translated into protein? a. mRNA, tRNA, and rRNA are all translated into protein. b. tRNA c. mRNA d. rRNA

c. mRNA

Mice that are injected with only the R strain of Streptococcus pneumoniae a. become sick for prolonged periods of time. b. are killed, because R strain cells are deadly. c. stay healthy, because their immune systems can kill this strain easily.

c. stay healthy, because their immune systems can kill this strain easily.

When the cell is not in the presence of lactose, a. the repressor proteins are inactivated. b. no transcription of the regulatory genes occurs. c. the repressor proteins bind to the operator. d. transcription of the structural genes occurs.

c. the repressor proteins bind to the operator.

How can hospital personnel prevent the spread of resistant E. faecium throughout the hospital? a. Hospital staff should wear shoe covers for the duration of their shift. b. Hospital staff should wear masks when entering a patient's room. c. Hospital staff should never serve raw fruit and salads to patients. d. Hospital personnel should wash their hands when entering and leaving a patient's room.

d. Hospital personnel should wash their hands when entering and leaving a patient's room.

Which of the following describes how 5-bromouracil might create a mutation? a. It can form thymine dimers. b. It creates bulges in the DNA that must be repaired. c. It causes double-stranded breaks of the DNA. d. It can replace the base thymine, and can base pair with guanine rather than adenine.

d. It can replace the base thymine, and can base pair with guanine rather than adenine.

Which of the following is an example of horizontal gene transfer in bacteria? a. Transduction b. Conjugation and transformation c. Conjugation d. Transduction, conjugation, and transformation e. Transformation

d. Transduction, conjugation, and transformation

Base-excision repair is a DNA repair mechanism designed to cope with which of the following types of problems in a cell? a. damage from mutagenic chemicals b. chromosome breaks c. damage from UV light d. errors in incorrect nucleotide incorporation

d. errors in incorrect nucleotide incorporation

A base substitution that changes a codon coding for an amino acid to a stop codon is called a a. frameshift mutation. b. missense mutation. c. silent mutation. d. nonsense mutation.

d. nonsense mutation.

What is the inducer molecule in the lac operon? a. Lactose b. Repressor proteins c. Glucose d. Galactose e. Allolactose

e. Allolactose

Insertions and deletions usually lead to which of the following types of mutations? silent mutations frameshift mutations base-substitution mutations pyrimidine dimers

frameshift mutations