smartwork ch 9

CRISPR-Cas9 may be used as a gene-editing tool to repair mutant genes (such as the gene that causes Huntington's disease in humans). This technique has been used in bacteria, mice, and even human embryos. First, CRISPR-Cas9 is used to target and remove the mutant gene. Second, naturally occurring repair enzymes will add the wild-type gene into the gap left from the site where the mutant gene was removed. Which of these bacterial repair mechanisms would most likely be responsible for repairing the DNA when used to edit bacterial genes? Choose one: A. RecA recombination repair B. UmuDC translesion bypass synthesis in SOS C. methyl mismatch repair D. nucleotide excisionE. base excision

A. RecA recombination repair

Which of the following does not function to reshape an organism's genome?Choose one: A. acquisition of genes from other organisms B. gene rearrangements C. spontaneous DNA mutations D. gene loss by deletion events E. lethal mutations

E. lethal mutations

The early stages of genome reduction in bacteria are normally characterized by the proliferation of pseudogenes. These most likely arise as a result ofChoose one: A. frameshift and nonsense mutations. B. conjugative plasmids. C. transforming DNA. D. transduced DNA. E. transposons.

A. frameshift and nonsense mutations.

The CRISPR systemChoose one: A. is a type of immunity that directs degradation of foreign DNA upon repeat exposure. B. unwittingly replicates bacteriophage DNA. C. facilitates recombination through a complex system of proteins and clustered repeats. D. randomly causes double-stranded breaks in any incoming DNA. E. promotes horizontal gene transfer following exposure to antibiotics.

A. is a type of immunity that directs degradation of foreign DNA upon repeat exposure.

Why are transposons so useful as genetic research tools? Choose one or more: A.They normally disrupt a single gene per cell. B.The mutations they cause have a high rate of reversion. C.They carry a selectable marker. D.The delivery plasmid is stably maintained in the recipient cell. E.They insert at random places in the genome.

A.They normally disrupt a single gene per cell. C.They carry a selectable marker. E.They insert at random places in the genome.

In bacteria, a partially diploid strain may result fromChoose one or more: A.acquisition of an F' factor. B.generalized transduction. C.specialized transduction. D.natural transformation (not electroporation). E.acquisition of F factor.

A.acquisition of an F' factor. C.specialized transduction.

Of the following processes, which two have the greatest impact on genome evolution in prokaryotes?Choose one or more: A.gene duplications B.gene inversions C.induced mutations D.horizontal gene transfer E.spontaneous mutations

A.gene duplications D.horizontal gene transfer

Uptake of foreign DNA can benefit a prokaryotic cell by serving as a source of which of the following?Choose one or more: A.nutrition B.terminal electron acceptors C.repair material D.quorum sensing signals E.novel genes

A.nutrition C.repair material E.novel genes

Which specific feature of replicative transposition distinguishes it from nonreplicative transposition?Choose one: A. It happens during replication of the chromosome. B. During replicative transposition, the entire transposon is replicated. C. It induces replication of the host chromosome. D. The target sequence is replicated as a result. E. Only the DNA internal to the inverted repeats of the transposon is replicated.

B. During replicative transposition, the entire transposon is replicated.

Which of the following is not a mechanism of horizontal gene transfer in bacteria?Choose one: A. transduction B. binary fission C. conjugation D. transformation

B. binary fission

All of the following are potential mechanisms of horizontal gene transfer exceptChoose one: A. specialized transduction. B. binary fission. C. transformation. D. conjugation. E. generalized transduction.

B. binary fission.

Consider the complex transposon in the above illustration. Suppose you discover a derivative of this element that replicatively inserts into target DNA but then becomes "stuck" as part of a cointegrate. Your graduate student sequences the respective gene products and finds no change in the primary amino acid sequences of the encoded enzymes. In which locus must the defect lie?Choose one: A. tnpR B. res C. tnpA D. in one (or both) of the inverted repeats E. bla

B. res

Consider conjugation in E. coli. In which of the following matings would chromosomal genes most likely be transferred?Choose one: A. F' x F+ B. F- x F- C. Hfr x F- D. Hfr x F+ E. F+ x F-

C. Hfr x F-

Select the true statement regarding the relationship between genotype and phenotype.Choose one: A. Some mutations will cause a change in the genotype, while others will not. B. Only genes that produce proteins are considered part of an organism's genotype. C. The phenotype reflects only the portion of the genotype that is expressed. D. The phenotype represents the entire genome of an organism. E. Any change in the genotype will be reflected in the phenotype.

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

Which of the following is an example of horizontal gene transfer in bacteria that requires cell-to-cell contact?Choose one: A. transformation B. transduction C. conjugation D. binary fission

C. conjugation

Consider a modification of the Ames test in which a suspected mutagen produced no reversions to histidine prototrophy in the tested Salmonella strain (above that of the control), but a significant increase in the number of revertants was observed when the compound was preincubated with liver extract. These results indicate thatChoose one: A. the compound promotes mutations in liver enzymes. B. the compound was detoxified by liver enzymes. C. the compound may become mutagenic after being metabolized by the liver. D. liver extract is highly mutagenic.

C. the compound may become mutagenic after being metabolized by the liver.

What two conditions must be met to produce a heritable mutation?Choose one or more: A.The change must result in a change in cellular phenotype. B.The change must occur within a particular gene. C.The mutation does not get repaired before the cell divides. D.Some form of horizontal gene transfer is involved. E.There is a change in the DNA sequence.

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

D. UV light.

Consider the reaction shown in the above illustration. This event is a potential source of mutations and results from exposure toChoose one: A. reactive oxygen species. B. acridine orange. C. X-rays. D. UV light. E. base analogs.

C. spontaneous depurination of DNA.

Consider the reaction shown in the above illustration. This is an example ofChoose one: A. a deletion mutation. B. CRISPR/Cas degradation of DNA. C. spontaneous depurination of DNA. D. base excision repair of DNA. E. restriction enzyme cleavage.

In addition to acquiring genes via conjugation, transduction, and transformation, natural selection may also favor loss of genes from an organism's genome. In which of the following bacteria would you most likely expect to find evidence of beneficial genome reduction?Choose one: A. free-living soil bacterium B. opportunistic pathogen C. harmless gut commensal D. obligate intracellular pathogen E. aquatic stalked bacterium

D. obligate intracellular pathogen

In 1928, a physician named Frederick Griffith was investigating the virulence of Streptococcus pneumoniae. He first determined that mice exposed to an encapsulated strain of S. pneumoniae (which formed smooth colonies) died. Mice infected with a nonencapsulated strain (which formed rough colonies) lived. In a now-famous experiment, he coinjected mice with heat-killed cells of virulent S. pneumoniae and cells from a live nonencapsulated strain. Amazingly, the mice died and a live virulent strain was recovered that formed smooth colonies. It was later discovered thatChoose one: A. the injected cell preparations were contaminated with live virulent S. pneumoniae. B. the live harmless cells mutated into a virulent strain once in the mice. C. the mice had subclinical infections of S. pneumoniae and became sick during the experiment. D. the live cells were transformed with DNA from the dead virulent cells. E. the dead virulent cells were resurrected once inside the living host.

D. the live cells were transformed with DNA from the dead virulent cells.

A.Bacterial chromosome B.Bacteriophage C.Phage DNA D.Methylation sites E.Restriction enzyme

Examine and correctly label the following illustration of a bacterial restriction and modification system.

D. conjugation

Identify the form of horizontal gene transfer depicted here.Choose one: A. transduction B. binary fission C. transformation D. conjugation E. electroporation

transversion; nonsense

The above illustration shows an example of a(n) ______________ mutation that results in a(n) _____________ mutation.

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

A(n) ________ mutation is one in which a single nucleotide has been substituted for another.

point

Most bacteria contain __________ enzymes that protect the cell from foreign DNA.

restriction

Genomic islands are large regions of DNA that confer traits such as pathogenicity, symbiotic competence, antibiotic resistance, and overall fitness. Evidence that genomic islands are acquired by horizontal gene transfer comes in part from observations that they are frequently found near __________ genes and have flanking ___________________

tRNA; direct repeats