Microbiology chp 8 Bacterial Genetics

Direct selection involves inoculating cells onto growth media on/in which

the mutant but not the parental cell type will grow.

Segments of DNA capable of moving from one area in the DNA to another are called

transposons

Following base removal, DNA polymerase can add nucleotides in the 5' to 3' direction.

true

Improper base-pairing during DNA replication causes a pause in chain elongation.

true

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

A transposon can move from the host chromosomal DNA to a plasmid.

true

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

transposons

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

transposons

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

transformation conjugation transduction

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

spontaneous mutations

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

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

Plasmids

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

transformation

On which of the following DNA strands would UV radiation have the most effect?

AATTAGTTC

Which change in a gene's DNA sequence would have the least effect on the eventual amino acid sequence produced from it?

Addition or deletion of three consecutive nucleotides

The material responsible for transformation was shown to be DNA by

Avery, MacLeod, and McCarty.

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

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

F'

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'

_______ 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

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

Which of the following types of repair does not require the standard DNA polymerase with proofreading capability?

SOS repair

Which of the following is FALSE about transposons?

They are capable of moving independently from one cell to another cell.

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

Transduction

Which of the following statements about transformation is correct?

Transformation is the uptake of naked DNA from the environment.

______ 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

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

Cancer-causing chemicals are called

carcinogens

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

carcinogens; mutagens

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

cell death cancer (in animals)

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

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

conjugative

Conjugation in bacteria requires ______.

contact between donor and recipient cell

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

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

direct; indirect

Transposons are composed of amino acids.

false

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

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

The proofreading function of DNA polymerase reduces the error rate from about one in a million base pairs to about one in a ______ base pairs.

hundred million

Chemical mutagens often act by altering the

hydrogen bonding properties of the nucleobase.

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

indirect

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

induced

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 horizontal gene transfer

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

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

proofreading mismatch

A clever technique that streamlines the identification of auxotrophic mutants is

replica plating

Which of the following are 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

Transposons are

segments of DNA

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

spontaneous

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

transduction

The mechanism by which genes are transferred into bacteria via viruses is called

transduction

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

transformation

Restriction-modification systems were discovered ______.

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

DNA polymerases use their ______ activity to remove a mismatched base pair.

3' -> 5' exonuclease

Bacterial cells that have been genetically modified to carry an antibiotic resistance gene can be separated from susceptible (non-resistant) microbes by using a ______ selection method using agar plates with antibiotic.

direct

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

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

direct indirect

In conjugation, transformation, or transduction, the recipient bacteria is most likely to accept donor DNA

from the same species of bacteria.

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

conjugation

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

conjugation transformation transduction

Which of the following are caused by chemical mutagens?

base substitutions frameshift mutations

Chemical mutagens can cause two types of mutations: __________ substitutions and _________ mutations.

base frameshift

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

conjugation

The transfer of vancomycin resistance from Enterococcus faecalis to Staphylococcus aureus is thought to have involved

conjugation AND transposons.

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

natural selection