Microbiology Chapter 8

Mutations in the DNA can be caused by both external factors (e.g. mutagens) and internal errors in DNA replication.

True

Horizontal gene transfer only occurs in eukaryotic organisms.

False

A point mutation involves the addition or removal of a single nucleotide base pair in the DNA sequence.

True

Mutagens are substances that increase the rate of mutation in an organism’s DNA.

True

Base analogs can mimic DNA bases and cause incorrect base pairing during DNA replication.

True

UV light forms thymine dimers

which are a type of chemical bond between adjacent thymine bases in DNA.

Excision repair involves removing incorrect bases and replacing them with the correct ones.

True

Transformation involves the uptake of DNA from the environment by a cell.

True

The Ames test is used to determine if a substance is a mutagen by observing its effect on a bacterial strain.

True

Transduction is the process of DNA transfer between bacterial cells via a bacteriophage.

True

Transposons can move within the genome and are often responsible for causing mutations.

True

Conjugation is the transfer of genetic material between bacterial cells via direct physical contact.

True

Mismatch repair fixes mismatched base pairs during DNA replication.

True

Base substitution mutations always result in a change in the amino acid sequence of a protein.

False

The Ti plasmid can transfer genes between bacteria and plants

creating natural GMOs.

Horizontal gene transfer can occur between different species of bacteria

contributing to antibiotic resistance.

Photoreactivation is a repair mechanism that requires light to fix thymine dimers caused by UV light.

True

The wild type is the most common genetic sequence found in a population.

True

Competent cells are able to take up foreign DNA from their environment.

True

Direct selection involves identifying mutants by growing them in an environment that favors their growth.

True

A mutation that involves the substitution of one base pair for another is known as a mutation.

base substitution

The transfer of genetic material between bacteria via a bacteriophage is called .

transduction

In conjugation

a bacterium transfers its genetic material through a sex pilus.

A is a substance that causes mutations in an organism’s DNA.

mutagen

The test is used to determine whether a substance is a mutagen by observing its effect on bacteria.

Ames

The movement of a transposon within the genome is called .

transposition

The repair of thymine dimers caused by UV light using light energy is called .

photoreactivation

The process by which a bacterium takes up free DNA from the environment is known as .

transformation

A is a small segment of DNA that can move from one location to another within the genome.

transposon

The mutation can shift the reading frame of the genetic code by adding or removing nucleotides.

frame shift

The is the most common form of a gene in a population.

wild type

A is a microorganism that can synthesize all the essential metabolites it needs.

prototroph

A is a microorganism that requires external sources of certain metabolites.

auxotroph

The process by which bacterial cells communicate and transfer DNA is known as gene transfer.

horizontal

A is a mutation that changes a single base pair often leading to a change in the amino acid sequence.

point mutation

DNA is transferred from one bacterium to another through physical contact.

True

A is the protein that helps move a transposon within the genome.

transposase

The repair of incorrect base pairings that occur during DNA replication is called repair.

mismatch

Bacteria that are able to take up foreign DNA and incorporate it into their genome are called cells.

competent

A is a chemical that can replace a normal base in DNA

base analog

The phase occurs when bacteria run out of a preferred nutrient and begin utilizing other available nutrients.

stationary