Chapter 8 smartbook

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

mutation

Genetic change in bacteria occurs through which two mechanisms?

mutation and horizontal gene transfer

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

as a defense against phages

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

base; frameshift

Cancer-causing chemicals are called

carcinogens

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

carcinogens and mutagens

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

cell death, cancer in animals

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

competent

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'

Which of the following are systems bacteria can use to protect against invading DNA?

Restriction-modification CRISPR

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

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

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

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

conjugation

Match each characteristic with the appropriate nucleic acid molecule.

contains an origin of replication -> both plasmids and chromosomes made of double stranded RNA -> neither plasmids nor chromosomes typically do not encode genes essential to the life of the cell -> plasmids only found in all eukaryotes and prokaryotes -> chromosomes only

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

core

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

core genome

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

direct

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

indirect

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

indirect

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

induced

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

plasmids

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

plasmids

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

proofreading; mismatch

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

transformation

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

transposons

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

transposons

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

transposons

Which of the following types of radiation are mutagenic?

ultraviolet rays, X-rays

Restriction-modification systems were discovered _____.

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

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

spontaneous

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

spontaneous mutations

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

substitution

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

substitution

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

conjugation

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

transduction

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

transduction

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

transformation

Ultraviolet rays are chemical mutagens.

False (because ultraviolet rats are a form of radiation that is commonly used to induce mutations.)

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

transposons

CRISPR systems involve ______.

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

In prokaryotes, genes can be transferred from a donor to a recipient via three mechanisms: _______, ________, and _________.

Bacterial transformation; transduction, conjugation

Which of the following are caused by chemical mutagens?

Base substitutions, frameshift mutations

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

DNA glycosylase

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

DNA repair

Which of the following are the three main methods of gene transfer in bacteria?

Transduction, conjugation, transformation

Which of the following statements about transformation is correct?

Transformation is the uptake of naked DNA from the environment.

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

The type of DNA damage repair illustrated here is _______.

base excision 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

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

mismatch repair and proofreading by DNA polymerase

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

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

False

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

induced

Conjugation in bacteria requires ______.

contact between donor and recipient cell

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

direct

Mutant cells in bacterial cultures can be isolated by _________ selection and ________ selection methods.

direct and indirect

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

direct and indirect

A point mutation always leads to a shift of the reading frame from the point of mutation downstream.

False - a frameshift mutation involves a shift of the triplet sequence from the point of mutation downstream. A point mutation is a substitution of bases, not a shift in the reading frame.

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

SOS

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

competent

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

conjugative