MICRO MH Ch. 8

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

DNA repair

A bacteriophage consists of a genome made up of DNA or

RNA; protein

Extensively damaged DNA activates the

SOS

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

competent

Which of the following plasmids are self-transmissible?

conjugative plasmids only

Conjugation in bacteria requires ______.

contact between donor and recipient cell

is the nucleotide sequence in the DNA of a cell or an organism.

genotype

Replica plating is used in ______ selection to transfer an identical pattern of bacterial cells to both a nutrient agar and a glucose-salts agar plate.

indirect

gene transfer, DNA moves from one organism to another, while in

horizontal; vertical

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

natural selection

Which of the following are possible outcomes of a base substitution?

nonsense mutation synonymous mutation missense mutation

Which type of DNA repair is shown in this figure?

nucleotide excision repair

Donor and recipient bacterial cells are connected by a sex ______ during conjugation.

pilus

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

Transposons

Which of the following types of radiation are mutagenic?

Ultraviolet rays X-rays

The structure connecting these two cells is called an F

pilus conjugation

The type of DNA damage repair illustrated here is _______.

base excision repair

When describing conjugation in Gram-negative bacteria, a donor cell with an F ______ is considered F+, while that without this structure are termed F-.

plasmid

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

carcinogens; mutagens

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

spontaneous mutations

A base substitution that results in a codon that still codes for the wild type amino acid is called a(n) ______ mutation.

synonymous

True or false: A point mutation involves any substitution of a single nucleotide.

t

True or false: Incorporation of an incorrect nucleotide in a molecule of DNA results in a distortion of the DNA helix that can be detected by repair enzymes.

t

True or false: The native or wild type strain describes the typical phenotype of strains isolated from nature.

true

Recognition and repair of errors in nucleotide incorporation by DNA polymerase is called ______.

proofreading

The process of bacterial

transformation

Place the steps of DNA-mediated transformation into the correct order. Start with the earliest at the top.

1. Double 2.nucleases 3. single 4.strand

When bacteriophages replicate, phage components are synthesized in the host cell and assemble into new viruses ______.

within that cell before being released

______ is used to fix nucleotide incorporation errors that are missed by the proofreading function of DNA polymerase.

Mismatch repair

transduction results from a packaging error during the virus replication cycle, when a piece of bacterial DNA is included in the new virus particle.

Generalized

This figure depicts the interconversion between an F+ cell and a(n)

Hfr

structurally resemble nucleobases and can be mistakenly used when cells make nucleotides, which are then incorporated by DNA polymerase into DNA.

base analogs

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

conjugative

Ultraviolet radiation causes covalent bonds to specifically form between adjacent

thymine

Ultraviolet radiation causes a very specific type of DNA damage called ______.

thymine dimers

mutation occurs if a single base pair is changed during DNA synthesis.

point

is the change of a mutated genetic sequence back to its original, non-mutated form.

reversion

The most common type of mutation is base

substitution

Which of the following statements about transformation is correct?

Transformation is the uptake of naked DNA from the environment.

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

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

Which of the following are caused by chemical mutagens?

frameshift mutations base substitutions

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

is the observed characteristics of an organism.

phenotype

When horizontal gene transfer occurs between a donor and recipient cells, the resulting cells are called

recombinants

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

substitution

Chemical mutagens can cause two types of mutations:

base; frameshift

There are two types of transduction:

generalized specialized

Chemical mutagens that modify ______ increase the odds of incorrect nucleotide incorporation during DNA replication.

nucleobases

A bacterial virus is known as a(n) _______.

phage

Which of the following can be found in a bacteriophage?

protein coat DNA or RNA genome

In the most thoroughly studied example of bacterial conjugation, the term

F+ F-

Which of the following are characteristics of recombinants?

The have properties of both donor and recipient cells. They result from horizontal gene transfer.

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

spontaneous

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

induced

Plasmids, transposons and phage DNA are all examples of ______.

mobile genetic elements

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

cell death cancer (in animals)

Mutant cells in bacterial cultures can be isolated by

direct; indirect

Cancer-causing chemicals are called

carcinogens

In bacteria

conjugation

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

induced

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

transpoons

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

After new virus particles have assembled in the bacterial host cell, they are usually ______.

released as a result of host cell lysis

Mutagens that modify nucleobases change their

base; pairing

A bacterial cell described as

competent

The return of a gene from a mutated state to its original, non-mutated state is called a ______.

reversion

Plasmids that encode resistance to a variety of antimicrobial agents and heavy metals are called

R

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

Protection against the toxic effects of antimicrobial compounds or heavy metals is often encoded on plasmids called

R

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

direct

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

direct; indirect

Low copy number high copy number narrow host range broad host range

occur in one or a few omccur in many can replicate in only can replicate in many

Which of the following are examples of mobile genetic elements?

phage DNA genomic islands transposons plasmids

Plating bacteria in duplicate patterns on both a nutrient agar plate and a glucose-salts agar plate is an example of

replica

An origin of transfer is encoded by _______.

both conjugative and mobilizable plasmids

Contains an origin of replication made of double stranded RNA typically do not encode genes essential to the life of the cell found in all eukaryotes and prokaryotes

both plasmids and chromosomes neither plasmids nor chromosomes plasmids only chromosomes only

During bacterial conjugation, synthesis of a new strand of F plasmid DNA occurs in ______.

both the donor and recipient

Although mobilizable plasmids encode an origin of transfer, they lack other genetic information required for transfer. Under what circumstances can a mobilizable plasmid be transferred to another bacterial cell?

when a conjugative plasmid is present in the same cell

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

DNA glycosylase

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

transformation transduction conjugation

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

F prime

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'

In bacteria,

conjugation

is a virus that infects bacteria, and some can transfer bacterial genes from a donor cell to a recipient cell.

bacteriophage

Which of the following describes an organism's observable characteristics?

phenotype

Many DNA polymerases have the ability to detect and repair their own errors in nucleotide incorporation. This ability is called

proofreading

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

transposons

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

indirect

______ sometimes incorporates the incorrect nucleotide when generating a new strand of DNA during DNA ______; this leads to a detectable distortion in the DNA helix.

DNA polymerase; replication

True or false: Vertical gene transfer is the transfer of genes from one organism to another in a population, while horizontal gene transfer is the transfer of genes from parent cell to progeny.

F

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

indirect

In transformation, only one daughter cell inherits donor DNA. This is because ______.

only a single strand of donor DNA integrates into the recipient chromosome

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

transposons

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

Plasmids

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

SOS

This figure shows the steps of ______, a process that repairs thymine dimers by breaking the covalent bonds that have formed between adjacent thymines.

photoreactivation

An organism that has a mutation is called a

mutant

Which term refers to an organism that has a mutation?

mutant

Which of the following plasmids encodes all the necessary genetic information for transfer from one bacterial cell to another?

Conjugative plasmids only

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

core

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

core genome

Which of the following terms describes the sequence of nucleotides (genetic makeup) of an organism or a cell?

Genotype

mutation is a base substitution that does not change the encoded amino acid.

silent

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

transduction

The genetic transfer mechanism shown here is called

transformation

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

transformation conjugation transduction

The native or

wild type

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

False

True or false: Plasmids are insertion sequences that can lead to changes in genotype within a cell or between cells.

False

Place the steps of F plasmid transfer in the correct order. Start with the earliest at the top.

1. f 2. o 3. s 4. c

_______ 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

Base ______ structurally resemble nucleobases and can be mistakenly incorporated into nucleotides and then into DNA.

analogs

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

f

True or false: Ultraviolet rays are chemical mutagens.

f

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 type of transduction that can transfer any genes of a host cell is called ______ transduction.

generalized

Plasmids with a

low; high

A base substitution that results in a change in the amino acid encoded is called a(n) ______ mutation.

missense

mutation is a base substitution that changes the codon to one that specifies a different amino acid.

missense

A base substitution in a protein-encoding gene results in one of three possible mutation outcomes:

silent; missense; nonsense

Transduction exists in two kinds. What are they?v

specialized generalized

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

conjugation

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

direct

This figure shows a cell with an integrated F plasmid. If this plasmid is incorrectly excised, the result could be an F plasmid that carries along a portion of the bacterial chromosome. Such a cell would then be called a(n)

F prime

Repair of nucleotide incorporation errors during the process of DNA replication is accomplished by

proofreading; mismatch


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