Micro-Ch.8

Which of the following are caused by chemical mutatgens?

-frameshift mutations -base substitutions

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

-transformation (or bacterial transformation, or DNA-mediated transformation) -transduction -conjugation

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

DNA repair

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'

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

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

False Some F+ cells possess the F plasmid separate from their chromosomal DNA. Hfr cell are only those in which the plasmid is integrated into the chromosome

TRUE or FALSE- A point mutation always leads to a shift of the reading from the point of mutation downstream.

False- REASON: 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.

TRUE or FALSE- Ultraviolet rays are chemical mutagens.

False- Ultraviolet rays are a form of radiation that is commonly used to induce mutations.

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

Frameshift

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

Indirect or negative

Why type of DNA repair is shown in this figure

Nucleotide excision repair

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

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

Spontaneous

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

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

The type of DNA damage repair illustrated here is __________.

base excision repair

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)

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

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

conjugation, transformation, transduction

Conjugation in bacteria requires _____.

contact between donor and recipient cell

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

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

direct and indirect

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

direct or positive

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

direct; indirect

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

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

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 and 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

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

natural selection

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

photoreactivation -REASON: In excision repair, thymine dimmers are cut out, while photoreactivation, the covalent bond between adjacent thymines is broken.

______ 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

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

restriction-modification CRISPR

This image highlights a bacterial defense against invading bacteria called the ______- ______ system.

restriction; modification

CRISPR systems involve ______.

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

Teratogens are ______.

Chemicals that cause birth defects and are not necessarily mutagens.

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

Conjugative

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

DNA glycosylase

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

transduction

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

transduction

The genetic transfer mechanism shown here is called ______.

transformation or bacterial transformation

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

______ 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

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

Base, base pair, or nucleobase; frameshift

Transduction involves ______.

Transfer of DNA via bacteriophages.

Conjugation involves ______.

Transfer of DNA via pili.

Transposition involves ______.

Transfer of DNA via transposons or "jumping genes"

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

Transformation

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

Transformation

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 - jumping genes

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

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

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