Microbiology chapter 8

Repair of nucleotide incorporation errors during the process of DNA replication is accomplished by _____by DNA polymerase and by _______ repair.

Blank 1: proofreading Blank 2: mismatch

Genetic change in bacteria occurs through which two mechanisms? Multiple select question. mutation vertical gene transfer horizontal gene transfer

mutation horizontal gene transfer

During repair of oxidized guanine, which enzyme removes the damaged nucleobase from the sugar-phosphate backbone?

DNA glycosylase

Random genetic changes that result from normal cellular processes are ______.

spontaneous mutations

A(n) __________ is a change in the nucleotide sequence of DNA that is passed on to daughter cells.

Mutation

Organisms most fit to survive in a given environment will predominate because they can reproduce more rapidly than others. This phenomenon is called _______ ______

Natural selection

types of radiation are mutagenic?

X-rays Ultraviolet rays

The consequences of not repairing damaged DNA in cells include ______.

cell death cancer (in animals)

The consequences of not repairing damaged DNA in cells include what

cell death cancer (in animals)

The genes that are present in all strains of a given species are called the ______.

core genome

_______ selection is used to isolate an auxotroph from a prototrophic parent strain, because no selective medium exists to inhibit the parent.

indirect

The mechanism by which bacterial DNA is moved from one bacterium to another by a bacteriophage is called

transduction

three main methods of gene transfer in bacteria?

transformation transduction conjugation

Segments of DNA that can move to new positions within the genome of a single cell are called _________

transposons

Restriction-modification systems were discovered ______.

while studying why certain bacterial strains are relatively resistant to phage infection

bacterial defense against invading bacteria called the ____-____ system

Blank 1: restriction Blank 2: modification

In E. coli, less than 50% of the genes are found in all strains. These conserved genes are called the _____ genome

core

Errors by DNA polymerase that incorporate the wrong nucleotide into replicating DNA can be repaired quickly by which two mechanisms?

Mismatch repair Proofreading by DNA polymerase

Conjugation in bacteria requires ______.

contact between donor and recipient cell

Mutagens that are DNA segments that can insert into genes and thereby inactivate them are called ______.

transposons

In prokaryotes, genes can be transferred from a donor to a recipient via three different mechanisms:

transformation, transduction and conjugation

Mutations that arise naturally during cellular metabolism, and not as a result of exposure to mutation-causing agents, are called _________ mutations.

spontaneous

In humans, two of the genes associated with the development breast cancer encode enzymes involved in ______.

DNA repair

A(n) _______ mutation results from an insertion or deletion of nucleotides, leading to a shift of the reading frame from the point of mutation downstream.

Frameshift

Two methods used to identify mutants in a culture are ______ and ______ selection.

direct; indirect

Mutations that are caused by external influences such as radiation or chemicals are called ______ mutations.

induced

Which mechanism of gene transfer involves the uptake of "naked" DNA by competent bacterial recipient cells?

transformation

An auxotroph can be isolated from a prototrophic parent strain by ______ selection.

indirect

_______ is the transfer of bacterial DNA from a donor to recipient via a bacteriophage.

transduction

The process of bacterial involves the uptake of "naked" DNA by competent bacterial recipient cells.

transformation

Chemical mutagens can cause two types of mutations: _____substitutions and _____ mutations.

Blank 1: base, base pair, or nucleobase Blank 2: frameshift

Mutant cells in bacterial cultures can be isolated by ___ selection and _____ selection methods.

Blank 1: direct Blank 2: indirect

When an excision errors produces a plasmid containing both chromosomal and F plasmid DNA, the resulting plasmid is called a(n) plasmid.

F' or F prime

____________ mutations are genetic changes caused by factors from outside of the cell such as radiation or chemicals.

Induced mutation

The most common type of mutation is base _________ , where an incorrect nucleotide is incorporated during DNA replication.

Subsitution

In conjugation in E. coli, an Hfr cell refers to ______.

a cell in which the F plasmid has been integrated into the cell chromosome

Because CRISPR systems involve bacteria using retained segments of DNA to identify and destroy future invading phage DNA, these systems are a form of ______.

adaptive immunity

Many bacteria are able to recognize and destroy invading DNA. It is thought this ability evolved ______.

as a defense against phages

what are caused by chemical mutagens?

base substitutions frameshift mutations

A bacterial cell described as _______ can take up DNA from the surrounding environment..

competent

Cells that have the ability to take up DNA from the environment are called ______ cells.

competent

In bacteria, ______ refers to DNA transfer requiring cell to cell contact.

conjugation

The F or fertility plasmid contains genes that are required for bacterial ______.

conjugation

Mutants that can grow under conditions in which the parent (wild type) cells cannot are easily isolated by selection.

direct

Selecting penicillin-resistant mutants by plating them on a medium containing penicillin is an example of ______ selection.

direct

When integrated F plasmid DNA in an Hfr cell is excised from the chromosome, an excision error can result in the removal of chromosomal DNA along with the F plasmid DNA, creating a plasmid called ______.

f'

True or false: A point mutation always leads to a shift of the reading frame from the point of mutation downstream.

false

True or false: In bacterial conjugation, all F+ donor cells are high frequency recombinant (Hfr) cells.

false

True or false: Ultraviolet rays are chemical mutagens.

false

The process by which organisms best adapted to a given environment will predominate in that environment is called _______.

natural selection

systems bacteria can use to protect against invading DNA?

restriction-modification CRISPR

CRISPR systems involve ______.

retained segments of phage DNA used by bacteria to recognize and destroy future invading DNA

A plasmid that can directs its own transfer from donor to recipient cells is called a(n) plasmid.

conjugative

_____ are DNA segments that increase the rate of mutations by inserting themselves into genes and inactivating them.

Transposons

______ are segments of DNA that can move from one location to another in a cell's genome.

Transposons

Extensively damaged DNA activates the repair mechanism, which cannot always determine the correct nucleotide sequence, thus introducing mutations resulting from the repair process itself.

sos

______ repair is activated by extensive DNA damage and uses a polymerase that lacks proofreading ability, ultimately resulting in mutations.

sos repair

Base ______ mutations occur when an incorrect nucleotide is incorporated in place of another during DNA synthesis.

subsitution

Chemicals that cause cancer are known as ______, and most of them are ______.

carcinogens; mutagens

___________ are circular pieces of bacterial DNA that do not usually encode information essential to the life of a cell.

plasmid

Cancer-causing chemicals are called

carcinogens