MicroBio Chapter 8: Bacterial Genetics

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

indirect

Chemical mutagens that squeeze between base pairs and induce frameshift mutation are called ____.

intercalating agent

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

spontaneous mutations

Mutagens that are DNA segments that insert themselves into genes and inactivates them are called ____.

transposons

Chemical mutagens can cause which of the following? -Base substitutions -Frameshift mutations -Double stranded breaks -Thymine dilmers

-Base substitutions -Frameshift mutations

Recognition and repair of errors in nucleotides incorporation by DNA polymerase is called ____.

proofreading

Bacteria are a great model system for genetic studies because when they are grown to very high numbers is small volumes of sample media ____.

rare genetic changes that happen can be easily studied

Modified nucleobases can result in ____ if they are not repaired before DNA replication occurs.

base substitution

Genes into which transposons "jump" are usually ____ by the event.

inactivated

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

released as a result of host cell lysis

The common consequences of a ____ mutation is the appearance of an appearance of an early stop codon that produces a shortened and thus non-functional proteins

frameshift

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

Base analogs

Chemicals that cause cancer are called ____, and most of them are ____.

Blank 1: carcinogens Blank 2: mutagens

True of False: Vertical gene transfer is the transfer of gene from one organism to another in a population, while horizontal gene transfer is the transfer of genes from cell to progency

False

True or False: Ultraviolet rays are chemical mutagens.

False

The ____ is the observed characteristics of an organism.

Phenotype

A process that breaks the covalent bonds that have formed between thymines to create thymine dimers.

Photoreactivation

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

SOS

Spontaneous mutations are important because ____.

They allow populations of bacteria to adapt to a changing environment

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

True

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

True

____ are a type of radiation that can cause single and double stranded breaks in a DNA strand.

X rays

When treating tuberculosis, two or more antimicrobial medication are often prescribed because ____.

a sensitive cell is unlikely to become resistant to two medications simultaneously through separate spontaneous mutations

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

direct

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

missense

A base substitution that changes an amino acid-encoding is called a(n)____ mutation.

nonsense

Chemical mutagens that modify ____ increase the odds of incorrect nucleotides incorporation during DNA replication.

nucleobases

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

point

If a scientist is working with bacteria that have the typical phenotype of those isolated from nature, the bacteria are considered to be ____ type.

wild

A mutation frequently results in the production of a shortened and non-functional protein because a different set of codons is translated.

Frameshift mutation

The two types of transduction.

-Specialized -Generalized

The consequences of not repairing damaged DNA in cells include ____. -cell death -increased activity of the RNA polymerase -cells that have fewer mutations -cancer (in animals)

-cell death -cancer (in animals)

Mutations are rare because -damage to DNA is very uncommon event -mutated DNA cannot replicated, so it cannot be passed to progency -most damage is repaired before it is passed on to progency

-most damage is repaired before it is passed on to progency

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

reversion

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

silent

Bacteriophage can consist of ____. -Nucleus -DNA genome -Hybrids DNA/RNA genome -Membrane (envelope) -RNA genome -Protein coats (capsid)

-DNA genome -RNA genome -Protein coats (capsid)

Which is an agent that induces changes in DNA? -Mutation -Mutant -Mutagen

-Mutagen

Genetic change in bacteria occurs through which two mechanism?

-Mutation -Horizontal gene transfer

In bacterial conjugation, a donor cell with an F ____ is considered F+. -Plasmid -Fimbria -Chromosome -Complex -Pilus

-Plasmid

The distortion of DNA by thymine dimers directly blocks which of the following cellular process? -Translation -Transcription -Respiration -Replication

-Replication -Transcription

The general mechanism by which most bacteria routinely respond to new circumstances are _____ change and regulating ____ expression.

Blank 1: genetic Blank 2: gene

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

True or False: a point mutation always lead to a shift of one reading frame from the point of mutation downstream.

False

Term describes the sequence of nucleotides (genetic makeup) of an organism or a cell.

Genotype