mcb3020 4b 2

By using a mutagen, the mutation rate can be increased to one mutant cell out of approximately Blank______ cells. Multiple choice question. 10 to 100 1,000 to 1,000,000 10 million to 1 billion 10 billion to 1 trillion

1,000 to 1,000,000

Under normal growth conditions, the rate of naturally-occurring mutant cells is one mutant cell out of approximately ___ cells. Multiple choice question. 10 to 10^2 10^3 to 10^6 10^7 to 10^11 10^12 to 10^15

10^7 to 10^11

In bacteria, an insertion sequence (or IS element) is typically about what size? Multiple choice question. 75-160 base pairs 750-1600 base pairs 7500-16,000 base pairs 75-160 kilobase pairs

750-1600 base pairs

Which three types of mutations are classified as reversion mutations? Multiple select question. A mutation that causes the wild type strain to become a mutant strain. A second frameshift mutation that restores an original reading frame. A second mutation creates a codon that replaces the wild type amino acid with a similar amino acid. A second mutation that restores the original wild-type sequence. A second mutation that creates a different codon that codes for the wild type amino acid.

A second mutation creates a codon that replaces the wild type amino acid with a similar amino acid. A second mutation that restores the original wild-type sequence. A second mutation that creates a different codon that codes for the wild type amino acid.

Which three of the following statements are correct regarding conjugation in Gram-positive bacteria such as Enterococcus faecalis. Multiple select question. A sex pilus may not be required. Donor and recipient cells adhere directly to each other. The proteins involved are not related to those in Gram-negatives. The donor cell typically dies following gene transfer. Peptides are released to activate transfer genes.

A sex pilus may not be required. Donor and recipient cells adhere directly to each other. Peptides are released to activate transfer genes.

Which three statements apply to an F' plasmid? Multiple select question. An F' plasmid includes some chromosomal genes. A cell carrying an F' plasmid is always considered an Hfr cell. An F' plasmid is smaller than a normal F plasmid. An F' plasmid has been excised from a bacterial chromosome. An F' plasmid is an erroneously excised plasmid.

An F' plasmid includes some chromosomal genes. An F' plasmid has been excised from a bacterial chromosome. An F' plasmid is an erroneously excised plasmid.

Which scientist first described mobile genetic elements? Multiple choice question. Barbara McClintock Joshua Lederberg Rosalind Franklin Carl Woese

Barbara McClintock

There are two types of excision repair systems that correct damage that causes distortions in the DNA double helix: ___ excision repair and ___ excision repair.

Blank 1: base Blank 2: nucleotide

Match each component of the E. coli mismatch repair system with its function. DNA ligase DNA polymerase MutH MutS connects the newly synthesized DNA with the old DNA replaces nucleotides that were excised scans newly replicated DNA for mismatches removes DNA around a mismatch

DNA ligase: connects the newly synthesized DNA with the old DNA DNA polymerase: replaces nucleotides that were excised MutH: removes DNA around a mismatch MutS: scans newly replicated DNA for mismatches

Which three of these statements about nonsense mutations are correct? Multiple select question. Effects range from mild to complete loss of normal gene function. They are typically not as severe when they occur near the beginning of a gene. They cause the early termination of translation. They involve a single base substitution that changes a codon for one amino acid to a codon for a different amino acid. By definition, they always produce stop codons.

Effects range from mild to complete loss of normal gene function. They cause the early termination of translation. By definition, they always produce stop codons.

Which of these is the defining characteristic of an Hfr strain? Multiple choice question. F plasmid integrated into the host chromosome Multiple sex pili Efficient DNA replication F plasmid in the cytoplasm

F plasmid integrated into the host chromosome

An F plasmid that has been excised from a bacterial chromosome, and includes some chromosomal genes, is called a(n) ___. Multiple choice question. F- plasmid F+ plasmid F' plasmid Fc plasmid

F' plasmid

A key component of the SOS response is the destruction of a transcriptional repressor protein called _____. Multiple choice question. LexA LacI DinB RecA

LexA

Which two of these descriptions apply to auxotrophs? Multiple select question. They are chemoorganotrophs able to grow on a minimal medium containing only salts and a carbon source. They have a conditional phenotype. They are unable to grow on medium lacking a particular molecule, where the wild-type strain could grow. They are resistance mutants.

They have a conditional phenotype. They are unable to grow on medium lacking a particular molecule, where the wild-type strain could grow.

The diagram illustrates which type of DNA repair? Multiple choice question. recombinational repair mismatch repair direct repair excision repair

mismatch repair

Point mutations in a single base that result in a change to the amino acid encoded are called __ mutations

missense

A point mutation that involves a single base substitution and results in a change to the amino acid encoded by that codon is specifically called a _____. Multiple choice question. suppressor mutation conditional mutation nonsense mutation missense mutation

missense mutation

Transition mutations, which result in purine for purine substitution or pyrimidine for pyrimidine substitution, are ___ common than transversion mutations. Multiple choice question. more less

more

The T4 phage of E. coli is a virulent bacteriophage, meaning that it ___. Multiple choice question. carries toxins that cause disease in humans multiplies in and lyses its host after infection is resistant to bacterial restriction endonucleases inserts its genome into the chromosome of its host

multiplies in and lyses its host after infection

The general term for heritable changes in DNA sequence is

mutations

A missense mutation that has little to no effect on the activity of a gene product is called a(n) __ mutation.

neutral

A tautomeric form is an isomer of a nucleotide in which the _____ is changed. Multiple choice question. nitrogenous base deoxyribose phosphodiester bond

nitrogenous base

Point mutations that create a stop codon within a reading frame are called __ mutations.

nonsense

Silent, missense, nonsense, and frameshift are all common types of __ mutations.

point

A wild-type chemoorganotroph like E. coli able to grow on a minimal medium containing only salts and a carbon source is known as a(n) __. These wild-type strains may give rise to mutants incapable of survival without additional nutrients, like a particular amino acid.

prototroph

Which three of these factors contribute to the extreme radiation resistance of Deinococcus radiodurans? Multiple select question. complex, atypical electron transport chain radiation-resistant proteins thick cell wall blocks radiation several unique DNA repair mechanisms two homologous chromosomes proteins that quickly repair damage to genome

radiation-resistant proteins two homologous chromosomes proteins that quickly repair damage to genome

Which of these types of DNA damage are usually mended by direct DNA repair? Multiple select question. gaps in DNA thymine dimers distortions in the double helix alkylated bases

thymine dimers alkylated bases

Select the best definition of horizontal gene transfer. Multiple choice question. persistence of a gene that confers a survival advantage DNA transfer between animals that move on land transfer of genes from one independent, mature organism to another transfer of genes from parents to progeny

transfer of genes from one independent, mature organism to another

The process of taking up DNA from the surroundings, and maintenance of the DNA in a heritable form, is called

transformation

Which bacterial process is illustrated by the image? Multiple choice question. conjugation specialized transduction transformation generalized transduction

transformation

Nucleotide substitutions that result in purine for purine or pyrimidine for pyrimidine mutations are known as __ mutations.

transition

DNA segments that can repeatedly insert into one or more sites or into one or more genomes are called ___ elements.

transposable

Select three synonyms for genetic elements that can move around genomes by transposition. Multiple select question. introns transposable elements mobile genetic elements site-specific plasmids jumping genes

transposable elements mobile genetic elements jumping genes

An insertion sequence or IS element consists only of a pair of inverted repeats surrounding a gene coding for the enzyme _____. Multiple choice question. telomerase transposase transcriptase transductase

transposase

Which enzyme is encoded in insertion sequences, recognizes inverted repeats, and cuts DNA to remove a mobile genetic element? Multiple choice question. transposase restrictase protease integrase

transposase

The movement of a mobile genetic element is called ___

transposition

True or false: A mutation can prevent a gene from being expressed, even if the coding sequence is completely unchanged. True false question. True False

true

True or false: Lethal mutants can be recovered only if they are conditional mutants. True false question. True False

true

True or false: Most transposable elements contain a transposase gene and inverted repeats. True false question. True False

true

Another term for the transfer of genes from parents to progeny is ___ gene transfer.

vertical

The most prevalent form of a gene, and its associated phenotype, is called the _______. Multiple choice question. common type normal type wild type natural type

wild type

Which three statements regarding homologous recombination are correct? Multiple select question. RecA protein is involved. Recombinases recognize specific DNA sequences. It occurs only during meiosis. Similar or identical DNA strands are broken and reunited. It is the most common mechanism of DNA recombination.

RecA protein is involved. Similar or identical DNA strands are broken and reunited. It is the most common mechanism of DNA recombination.

Which example of a missense mutation in a protein-encoding gene would most likely be a neutral mutation? Multiple choice question. Replacement of a polar amino acid with a nonpolar amino acid at the protein's outer surface Replacement of a polar amino acid with another polar amino acid at the protein's surface Replacement of a polar amino acid with another polar amino acid in the protein's interior Replacement of a polar amino acid with a nonpolar amino acid in the protein's interior

Replacement of a polar amino acid with another polar amino acid at the protein's surface

When DNA damage is so great that DNA synthesis stops, a control system called the __ response occurs.

SOS

Which two of these statements are correct about frameshift mutations? Multiple select question. They usually yield mutant phenotypes. By definition, they always produce stop codons. They involve a single base substitution that changes a codon for one amino acid into another. They are typically not as severe when they occur near the beginning of a gene. They usually result in the synthesis of nonfunctional proteins.

They usually yield mutant phenotypes. They usually result in the synthesis of nonfunctional proteins.

A suppressor mutation, which returns a mutant back to its wild-type phenotype, occurs at ____________ the first mutation. Multiple choice question. a different site from the same site as

a different site from

A chemical agent that causes cancer is specifically called a(n) __

carcinogen

In bacteria, conjugation refers to the transfer of DNA by _____. Multiple choice question. direct uptake by the cell cell-to-cell contact bacteriophages "jumping genes"

cell-to-cell contact

A resistance mutant may have acquired resistance to which three of the following? Multiple select question. chemical pathogen transformation nutrient deficiency antibiotic

chemical pathogen antibiotic

A bacterial cell that is able to take up DNA and be transformed is said to be ___

competent

A mutant strain of E. coli that grows normally at 30°C, but dies at 40°C, is a(n)_________ mutant. Multiple choice question. silent prototrophic conditional nonsense

conditional

Mutations that are expressed only under certain environmental conditions are called ___ mutations.

conditional

The image shows horizontal transfer of bacterial DNA by the process known as _____. Multiple choice question. transposition conjugation transformation transduction

conjugation

Thymine dimers can be corrected by photoreactivation, which is a type of ___ DNA repair.

direct

True or false: Conjugation occurs only in Gram-negative bacteria. True false question. True False

false

Hfr strains of bacteria are so named because they undergo a ___(high/low) frequency of ___

high, recombinants

The most common type of DNA recombination (e.g., during meiosis or bacterial horizontal gene transfer) is ___ recombination between similar or identical DNA strands.

homologous

Mechanisms that result in the transfer of genes from one independent, mature organism to another are collectively called ___ gene transfer.

horizontal

Transposases are enzymes that recognize the ends of a(n) _______. Multiple choice question. promoter rRNA protein-encoding gene insertion sequence

insertion sequence

The type of mutation that affects only a single base pair at a given DNA location is called a(n) __ mutation.

point

The ability of DNA polymerase to detect and correct errors before the next nucleotide is added is called __

proofreading

Damage to DNA in which both bases of a pair are missing or damaged, or where there is a gap opposite a lesion, is usually repaired by a process called __ repair.

recombinant

Which type of DNA repair is shown in the image? Multiple choice question. excision repair SOS response direct repair recombinational repair

recombinational repair

Which two of these missense mutations would be predicted to have the most severe effects on the function of the protein encoded by the mutated gene? Multiple select question. replacement of a nonpolar amino acid with a polar amino acid substitution of an amino acid located at the active site of an enzyme replacement of an amino acid located in a surface loop of an enzyme replacement of a hydrophobic amino acid with a different hydrophobic amino acid

replacement of a nonpolar amino acid with a polar amino acid substitution of an amino acid located at the active site of an enzyme

An allele is most likely to persist in a population if it confers a survival advantage under _________ pressure. Multiple choice question. reductive selective extinction lethal

selective

Point mutations that change the nucleotide sequence of a codon but do not change the amino acid encoded by that codon are called __ mutations.

silent

Mutations that result from the activity of mobile genetic elements called transposons are considered to be which type of mutations? Multiple choice question. Spontaneous Induced Transition Point

Spontaneous

Which two statements correctly describe missense mutations? Multiple select question. By definition, they always produce stop codons. They are typically not as severe when they occur near the end of a gene. They cause the early termination of translation. They are a single base substitution that changes a codon for one amino acid into a codon for a different amino acid. Effects range from no change to complete loss of normal gene function.

They are a single base substitution that changes a codon for one amino acid into a codon for a different amino acid. Effects range from no change to complete loss of normal gene function.

Alternative forms of a gene are called __

allele

Which of these descriptions applies to prototrophs? Multiple choice question. They have a conditional phenotype. They are chemoorganotrophs able to grow on a minimal medium containing only salts and a carbon source. They are unable to grow on medium lacking a particular molecule, where the wild-type strain could grow. They are able to use light as an energy source.

They are chemoorganotrophs able to grow on a minimal medium containing only salts and a carbon source.

Which of the following statements about viruses and transduction is false? Multiple choice question. All cellular organisms are susceptible to viral infections. Viruses escaping a bacterium can find a new host cell and move genes to an archaeon. Viruses can move genes from one bacterium to another in natural environments. Transduction is a natural consequence of the viral life cycle and requires no special host cell structures.

Viruses escaping a bacterium can find a new host cell and move genes to an archaeon.

Select two examples of mutations that affect regulatory sequences of microbial genes. Multiple select question. a mutation that affects the ability of transfer RNA to bind to a particular amino acid a mutation in a promoter so that RNA polymerase cannot bind a mutation in a ribosomal RNA gene that alters the structure of 30S ribosomes a mutation in the lac operator so the lac repressor cannot bind a mutation that affects the active site of β-galactosidase

a mutation in the lac operator so the lac repressor cannot bind a mutation in a promoter so that RNA polymerase cannot bind

An organism with a mutation that affects its ability to synthesize a biochemical essential for its growth is known as a(n) __

auxotroph

An organism with a mutation that affects its ability to synthesize a biochemical essential for its growth is known as a(n) ___

auxotroph

Match each type of mutation with the appropriate example. Instructions auxotroph conditional morphological resistance mutation affects the appearance of colonies mutant cannot synthesize an essential molecule such as an amino acid phenotype is only affected at high temperatures mutant is not affected by a particular pathogen or chemical

auxotroph: mutant cannot synthesize an essential molecule such as an amino acid conditional: phenotype is only affected at high temperatures morphological: mutation affects the appearance of colonies resistance: mutant is not affected by a particular pathogen or chemical

The most straightforward example of screening for a mutant phenotype would be Blank______. Multiple choice question. detecting a bacterium that has a mutated tRNA molecule detecting a mutant that has lost the wild type pigmentation detecting a bacterium that is non-motile detecting a histidine auxotroph

detecting a mutant that has lost the wild type pigmentation

DNA proofreading occurs ___. Multiple choice question. after DNA replication is complete and mismatched nucleotides are detected during DNA replication, before the next nucleotide is added only after errors in transcription are detected before DNA replication begins, to make sure all nucleotides are correctly matched

during DNA replication, before the next nucleotide is added

Possible causes of spontaneous mutation include Multiple select question. errors in DNA replication spontaneous lesions in DNA transposons chemical agents physical agents

errors in DNA replication spontaneous lesions in DNA transposons

Which type of DNA repair corrects damage (e.g., thymine dimers) that causes distortions in the DNA double helix? Multiple choice question. excision repair recombinational repair mismatch repair proofreading

excision repair

True or false: The Ames test can determine whether a particular substance is carcinogenic. True false question. True False

false

William Hayes' 1952 experiments demonstrated that conjugation is unidirectional and identified strains he named F+ and F-. The "F" stands for

fertile or fertility

A mutation that leads to a change from wild type to a mutant form is called a(n) __ mutation.

forward

Vertical gene transfer can be best defined as the transfer of genes _____. Multiple choice question. from progeny to parents between any two individuals of different species between any two individuals of the same species from parents to progeny

from parents to progeny

The major conclusion of Hayes' 1952 experiments, which demonstrated the existence of F+ and F- strains, was that _____. Multiple choice question. gene transfer by conjugation is bidirectional gene transfer by conjugation is unidirectional gene transfer by transformation is bidirectional gene transfer by transformation is unidirectional

gene transfer by conjugation is unidirectional

The image shows horizontal transfer of bacterial DNA by what process? Multiple choice question. transposition transformation specialized transduction generalized transduction

generalized transduction

Select three examples of chemical mutagens. Multiple select question. intercalating agents high temperature ribonucleotides UV radiation DNA-modifying agents DNase base analogs

intercalating agents DNA-modifying agents base analogs

Which two of these features are common to all transposable elements? Multiple select question. inverted repeats gene for antibiotic resistance gene for resolvase reverse transcriptase gene for a recombinase (e.g., transposase)

inverted repeats gene for a recombinase (e.g., transposase)

Mobile genetic elements were discovered by Barbara McClintock in the 1940s, during her studies of what organism? Multiple choice question. maize fruit flies peas E. coli

maize

The bacterium Deinococcus radiodurans is best known for its ability to ________. Multiple choice question. resist damage by radiation form endospores resist damage by heat cause disease in plants

resist damage by radiation

A mutant that can survive exposure to some pathogen, chemical, or antibiotic, is a(n) __ mutant.

resistance

The use of a detection system to locate a microbe with a particular mutant phenotype is generally known as ____. Multiple choice question. panning sorting filtering screening

screening

A mutation that caused the codon CGU to change to CGC, which does not affect the amino acid encoded, could be described by which two of these terms?

silent point

Select the best definition of transposable elements. Multiple choice question. bacteriophages that contain both phage and bacterial DNA, usually the result of lysogenization small DNA molecules within a cell that are physically separated from a chromosomal DNA and can replicate independently short segments of DNA flanked by inverted repeats, that contain only the gene for transposase specific DNA segments that can repeatedly insert into one or more sites or into one or more genomes

specific DNA segments that can repeatedly insert into one or more sites or into one or more genomes

Mutations that result from the activity of mobile genetic elements called transposons are considered to be which type of mutations? Multiple choice question. Spontaneous Point Transition Induced

spontaneous

A second mutation that occurs at a different site from the first mutation, and which returns the mutant back to the wild-type phenotype, is a(n) __

suppressor

If a bacterial cell is competent, that means it can _____. Multiple choice question. synthesize all required structural components take up DNA and become transformed repair its DNA efficiently and effectively perform all normal metabolic pathways

take up DNA and become transformed

Spontaneous mutations can occur when a nitrogenous base shifts to a different isomer, also called a(n) ____. Multiple choice question. monomeric form polymeric form tautomeric form allosteric form

tautomeric form

In bacterial genetics, transformation is ___. Multiple choice question. the transfer of bacterial DNA by cell-cell contact the transfer of bacterial DNA by a bacteriophage another term for "jumping genes" the uptake of free DNA by a bacterial cell

the uptake of free DNA by a bacterial cell