Ch 10 Mastering Microbiology

Which of the following attaches the target gene to a desired location? Chromosomal DNA Plasmids Restriction enzymes DNA ligase

DNA ligase

The killing of cells by UV irradiation involves absorption at 260 nm by proteins only. formation of pyrimidine dimers. formation of purine dimers. absorption at 260 nm by RNA only.

forming of pyrimidine dimers

Microinsertions and microdeletions often result in ________ mutations. silent advantageous auxotrophic frameshift

frameshift

Increasing genetic variability by the uptake of DNA from the environment is __________. a mutation conjugation transduction transformation

transformation

Intercalating agents, like acridine orange and ethidium bromide, lead to mutagenesis by pushing DNA base pairs apart, which can lead to insertions or deletions. True False

true!

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

A bacterial plasmid

The genetic code is degenerate. Which of the following answers describes an example of the degenerate nature of the code? The sequence "AUGCCGAUU" is read as three codons, AUG, then CCG, then AUU. AUU, AUC, and AUA all code for Ile There are no pauses or commas in the code. AUU codes for Ile in a wide variety of species

AUU, AUC, and AUA all code for Ile

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

Both simple and complex transposons

How do complex transposons differ from simple transposons? 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. Complex transposons are found in multiple locations in the target DNA; simple transposons are found only in one location. Complex transposons code for transposase; simple transposons do not.

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.

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

Conjugation does not result in the formation of new offspring.

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

Conjugation is a process of bacterial reproduction.

In specialized transduction, virtually any genetic marker can be transferred from donor to recipient. True False

FALSE SPECIALIZED TRANSDUCTION IS SPECIFIC AF

Laboratory-based genetic systems have been difficult to develop for Archaea, because they do NOT naturally undergo conjugation or transduction. True False

False

Penicillin selection is a positive selection for the isolation of mutants with growth factor requirements. True False

False

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

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

Transformation is a useful technique for making genetically modified bacteria in the laboratory. There have been efforts to transform Archaea, but it has been more difficult than transforming Bacteria. One reason that it has been difficult is that Archaea lack a peptidoglycan cell wall. Why does that affect the ability of researchers to develop techniques to transform them? Relatively few viruses have been identified that infect Archaea. It is difficult to create auxotroph strains of Archaea. Genes for resistance to penicillin and related antibiotics can't be used as selectable markers. Many Archaea are extremophiles and require conditions that are difficult to create in the lab.

Genes for resistance to penicillin and related antibiotics can't be used as selectable markers

Why would a recombinant DNA molecule be inserted into a host cell? It can protect the recombinant DNA. Restriction enzymes can only be used inside of a cell. Plasmids cannot be isolated outside of a host cell. It can be copied, transcribed, and translated into a desired protein.

It can be copied, transcribed, and translated into a desired protein.

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

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

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? The S strain was revived by the presence of the host's immune system. The R strain cells picked up the capsules from the S strain cells. The R strain picked up the S strain DNA, enabling it to produce a capsule. The S strain fused with the R strain, making it resistant.

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

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

The cells have a capsule.

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

The cells must come into contact with each other.

Which of the following would result in a frameshift mutation? The deletion of three nucleotides in a codon The deletion of two nucleotides in a codon The addition of three nucleotides between two existing codon. The deletion of one nucleotide from one codon and two nucleotides from the adjacent codon

The deletion of two nucleotides in a codon

A single base substitution happens to cause a nonsense mutation early in the gene for a protein. What will be the result? The protein will be truncated so much that it is unlikely to function normally. The protein will be truncated a small amount, but is likely to function normally. The protein will be truncated a great deal, but is likely to function normally. The protein will be truncated a small amount, but is unlikely to function normally.

The protein will be truncated so much that it is unlikely to function normally.

How do restriction enzymes cut DNA sequences? They have the ability to cut DNA randomly. They cut DNA at sequences that have lots of adenine bases. They cut DNA at sites, called recognition sites, that have specific nucleotide sequences.

They cut DNA at sites, called recognition sites, that have specific nucleotide sequences.

In a culture of bacteria, there are some individuals that are unable to synthesize histidine. What is the best and most likely description of how these individuals differ from the other bacteria in the culture? They differ in their genotype and in their phenotype. They differ in their genotype but not in their phenotype. They differ in their phenotype but not in their genotype. They don't differ in genotype or phenotype.

They differ in their genotype and in their phenotype.

In general, how might recombinant DNA technology be used to prevent a genetic disorder caused by a mutation in a single gene? To insert a desirable gene, remove an undesirable gene, or replace a defective gene with a functioning gene To replace a defective gene with a working gene To insert a desirable gene To remove an undesirable gene

To insert a desirable gene, remove an undesirable gene, or replace a defective gene with a functioning gene

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

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

Frameshift mutations can be very severe. What is one reason why they are often so serious? Frameshift mutations always occur in the regulatory region, so they cause a gene to be turned off and then the protein is not produced at all. When a frameshift mutation occurs, it causes changes in many bases upstream and can affect many of the amino acids in the protein. When a frameshift mutation occurs, it causes changes in many bases downstream and can affect many of the amino acids in the protein. When a frameshift mutation occurs, it causes transition mutations to occur. These are particularly severe.

When a frameshift mutation occurs, it causes changes in many bases downstream and can affect many of the amino acids in the protein.

A "point mutation" refers to mutations involving the deletion of a base pair (microdeletion). a base-pair substitution. a substitution, deletion, or addition of one base-pair. the gain of a base pair (microinsertion).

a substitution, deletion, or addition of ONE base-pair (insertion)

An organism that cannot synthesize methionine is called __________. a mutant an autotroph an auxotroph a prototroph

an auxotroph

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

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

Lysogeny probably carries a strong selective advantage for the host cell because it prevents cell lysis. confers resistance to infection by many virus types and prevent cell lysis. confers resistance to infection by viruses of a different type (or strain). confers resistance to infection by viruses of the same type.

confers resistance to infection by viruses of the same type.

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

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

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? nonsense mutation missense mutation frameshift mutation silent mutation

frameshift mutation

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

it has no effect on the overall amino acid sequence

If a bacterium carrying a plasmid that confers resistance to ampicillin is placed into medium WITHOUT ampicillin, it may gain resistance to other antibiotics. undergo a reversion mutation. transfer resistance to other cultures in the laboratory. lose the plasmid because there is no selection for ampicillin resistance.

lose the plasmid because there is no selection for ampicillin resistance. (aka doesnt need to be resistant to the antibiotic because its not there in the medium)

A change in the base sequence of DNA that is passed on to daughter cells is __________. a mutation of no consequence lethal a mistake

mutation

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? silent mutation deletion mutation missense mutation nonsense mutation

nonsense mutation

The mutagens 2-aminopurine and 5-bromouracil are examples of nucleotide base analogs. chemicals reacting with DNA. alkylating agents. None of the answers are correct.

nucleotide base analogs.

The designations Phe-, Leu-, and Ser+ refer to an organism's genotype. plasmid type. mutation type. phenotype.

phenotype.

A mutation that readily reverses to restore the original parental type would most likely be due to a(n) insertion. point mutation. deletion. frameshift mutation.

point mutation.

Consider a mutation in which the change is from UAC to UAU. Both codons specify the amino acid tyrosine. Which type of point mutation is this? silent mutation nonsense mutation frameshift mutation missense mutation

silent mutation

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

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

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

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

Which process listed below does NOT require homologous recombination to maintain the new genetic material in the recipient cell? conjugation of a linear piece of DNA transformation of a linear piece of DNA gene transfer through a genetic transfer agent transduction by a dsDNA phage Mu

transduction by a dsDNA phage Mu bc vius injects it it doesnt need to be incorporated into a host chromosome just lives in the phage man