Microbiology Chapter 8

The properties of a cell which are determined by its DNA composition are its phenotype. genotype. metabolism. nucleoid.

The source of variation among microorganisms that were once identical is antibiotic resistance. virulence factors. sigma factors. mutation.

The characteristics displayed by an organism in any given environment is its genotype. archaetype. mutatotype. phenotype.

The designation his- refers to the genotype of a bacterium that lacks a functional gene for histidine synthesis. the genotype of a bacterium that has a functional gene for histidine synthesis. the opposite of a hers gene. bacteria that are auxotrophic for histidine. the genotype of a bacterium that lacks a functional gene for histidine synthesis AND bacteria that are auxotrophic for histidine.

Segments of DNA capable of moving from one area in the DNA to another are called base analogs. intercalating agents. transposons. palindromic sequences.

Transposons are informally known as jumping genes. may cause insertion mutations. may cause knockout mutations. were first recognized in plants. All of the choices are correct.

Chemical mutagens often act by altering the alkyl groups of the nucleobase. nucleobase sequence. number of binding sites on the nucleobase. hydrogen bonding properties of the nucleobase.

The largest group of chemical mutagens consists of radiation. base analogs. nitrous acid. alkylating agents.

Nitrous acid most frequently causes mutations by substituting oxygen for hydrogen bonds. converting keto groups to amino groups. altering the bonding ratios of nitrogen bases. converting cytosine to uracil.

Chemical mutagens that mimic the naturally occurring bases are called nitrogen mustards. alkylating agents. base analogs. nitrous oxide.

Planar molecules used as chemical mutagens are called nitrous oxide. base analogs. alkylating agents. intercalating agents.

Intercalating agents act during DNA synthesis. often result in frame shift mutations. only act in dormant cells. alter the hydrogen bonding properties of the bases. act during DNA synthesis AND often result in frame shift mutations.

Irradiation of cells with ultraviolet light may cause 4 nucleotides to covalently bind together. thymine dimers. adenine complementary base pairing with cytosine. the addition of uracil.

Thymine dimers are dealt with by no repair mechanisms. photoreactivation repair. SOS repair. excision repair. photoreactivation repair AND excision repair.

The formation of a covalent bond between two adjacent thymines is caused by mustard gas. alkylating agents. microwave radiation. UV radiation.

X-rays have no effect on DNA. cause thymine trimers. cause single and double strand breaks in DNA molecules. make the DNA radioactive.

DNA repair mechanisms occur only in prokaryotes. only in eukaryotes. in both eukaryotes and prokaryotes. in neither eukaryotes or prokaryotes.

Which is not true about mismatch repair? It utilizes an endonuclease. It requires DNA polymerase and DNA ligase. It utilizes the state of methylation of the DNA to differentiate between strands. It removes both strands in the mismatch area.

Antibiotics cause mutations to occur. may act as alkylating mutagens. provide an environment in which pre-existing mutants survive. increase the rate of spontaneous mutation.

Prokaryotic cell mutations can be observed very quickly because the prokaryotic chromosome is diploid. polyploid. haploid. polysomal.

The diploid character of eukaryotic cells may mask the appearance of a mutation since this may be a frame shift. the mutation is often reversible. the mutation may be palindromic. the matching chromosome may carry the dominant gene.

Direct selection involves inoculating cells onto growth media on which the mutant but not the parental cell type will grow. the mutation will be reversed. the nutrients necessary for mutation to occur are present. the mutagen is present.

A clever technique that streamlines the identification of auxotrophic mutants is gas chromatography. replica plating. direct selection. reversion.

To increase the proportion of mutants in a population of bacteria one may use direct selection. replica plating. penicillin enrichment. individual transfer.

A quick microbiological test for potential carcinogens was developed by Fleming. Lederberg. Ames. Crick.

To increase the chance of detecting carcinogens in the Ames Test, the test substance is treated with penicillin. heat. ground up rat liver. reverse transcriptase. penicillin AND heat.

The Ames test is useful as a rapid screening test to identify those compounds that will respond to chemical agents. are mutagens. respond to the deletion of DNases. will protect an organism from cancer. will respond to chemical agents AND will protect an organism from cancer.

Bacteria that have properties of both the donor and recipient cells are the result of UV light. SOS repair. frame shift mutations. genetic recombination.

The mechanism by which genes are transferred into bacteria via viruses is called ellipsis. replica plating. transformation. transduction. conjugation.

In conjugation the donor cell is recognized by the presence of an F plasmid. a Y chromosome. diploid chromosomes. an SOS response. an F plasmid AND diploid chromosomes.

The F plasmid carries the information for antibiotic resistance. recipient cell DNA replication. the Y chromosome. the sex pilus. antibiotic resistance AND the Y chromosome.

Competent cells are able to take up naked DNA. are antibiotic resistant. occur naturally. can be created in the laboratory. are able to take up naked DNA, occur naturally AND can be created in the laboratory.

The material responsible for transformation was shown to be DNA by Watson and Crick. Avery, MacLeod and McCarty. Lederberg. Stanley.

In conjugation, transformation, or transduction, the recipient bacteria is most likely to accept donor DNA from any source. from any species of bacteria. from the same species of bacteria. only through plasmids. from any source AND only through plasmids.

Gene transfer that requires cell-to-cell contact is transformation. competency. conjugation. functional genomics.

Insertion sequences are the simplest type of transposon. code for a transposase enzyme. are characterized by an inverted repeat. can produce pili. are the simplest type of transposon, code for a transposase enzyme AND are characterized by an inverted repeat.

The transfer of vancomycin resistance from Enterococcus faecalis to Staphylococcus aureus is thought to have involved conjugation. transformation. transduction. transposons. conjugation AND transposons.

Which is not true about a crown gall tumor? It is a bacterial infection of plants. It requires a plasmid. It produces a large amount of opines that neither the plant nor bacteria synthesizes. It is due to the incorporation of bacterial plasmid DNA into the plant chromosome. All of the choices are true.

The study of the crown gall tumor found a bacterial plasmid promoter that was similar to plant promoters. an R plasmid. incorporation of the bacterial chromosome into the plant. incorporation of the plant chromosome into the bacteria.

Organisms termed his- are considered prototrophic for histidine. True False

Each gene mutates at a characteristic frequency. True False

DNA polymerase is able to proofread the DNA sequence. True False

The Ames test determines antibiotic sensitivity of a bacterium. True False

Double-stranded DNA enters the recipient cell during transformation. True False

Plasmids often carry the information for antibiotic resistance. True False

F plasmids and oftentimes R plasmids are both able to code for production of a pilus. True False

Transposons may leave a cell by incorporating themselves into a plasmid. True False

Crown gall is caused by a prokaryote plasmid that can be expressed in plant cells. True False