MIC 205 Chapter 8

Transposons

"jumping genes", can lead to changes in genotype within a cell or between cells

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

base substitutions

Chemical mutations can cause _________

base substitutions and frameshift mutations

Why are spontaneous mutations important?

they allow populations of bacteria to adapt to a changing environment.

Two kinds of radiation are commonly used as mutagens are :

ultraviolet (UV) light and X rays.

mutagen

An agent that induces genetic change

SOS repair

Complex, inducible repair process used to repair highly damaged DNA. (last effort attempt)

Base analogs

Compound that structurally resembles a nucleobase closely enough to be incorporated into a nucleotide in place of the natural nucleobase.

Genes can be transferred from a donor to a recipient by what three different mechanisms?

DNA-mediated transformation, Transduction, and Conjugation.

What can be transferred from one cell to another by conjugation

Plasmid DNA and chromosomal DNA

Bacteriophages can consist of _____________-

RNA genome or DNA genome and a protein coat

Mismatch repair

Repair mechanism in which an enzyme cuts the DNA near a mismatched nucleobase, resulting in the removal and replacement of a short stretch of nucleotides.

A mutation is

a change in DNA that is passed on to daughter cells

Prototroph

an organism that does not require growth factors

After new virus particles have assembled in the bacterial host cell, they usually ________

are released as a result of host cell lysis

Chemicals that cause cancer are _______ and they are mostly _______

carcinogens; mutagens

The consequences of not repairing damaged DNA cells are

cell death and cancer in animals

Competent cells

cells that have the ability to take up DNA from the environment

Plasmids

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

Mobile Gene Pool

consists of genes that can move from one DNA molecule to another

Mutations are rare because ________________

damage is repaired before it is passed on to progeny.

Mutant cells in bacterial cultures can be isolated by what methods?

direct and indirect selection

R plasmids

encode resistance to antimicrobial chemicals, including antibiotics

Frameshift mutation

frequently results in the production of a shortened and nonfunctional protein because a different set of codons is translated

There are two types of transduction:

generalized and specialized

What describes the sequence of nucleotides (genetic makeup) of an organism/cell

genotype

In bacterial conjugation, F+ donor cells are high frequency recombinant (Hfr) cells when the F plasmid ________________.

is integrated into the chromosomes

Indirect selection

is used to isolate an auxotrophic mutant from a prototrophic parent strain.

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

What mutations are possible outcomes of a base substitution

missense mutation, silent mutation, and nonsense mutation

Point mutation

occurs if a single base pair is changed during DNA synthesis

During conjugation, donor and recipient bacterial cells are connected by a sex ____________

pilus

What are examples of replicons?

plasmid and chromosomes

Spontaneous mutations

random genetic changes that occur as a result of natural cellular processes

Proofreading

recognition and repair of errors in nucleotide incorporation by DNA polymerase

Bacteria routinely adapt to new circumstances by

regulating gene expression and genetic change

What are systems bacteria can use to protect against invading DNA?

restriction-modification and CRISPR

X rays can cause which type of damages to a DNA molecule?

single- and double-strand breaks in DNA, and changes to the nucleobases.

excision repair

the repair of thymine dimers by enzymes that make single-stranded cuts that flank both sides of the thymine dimer.

Genomic islands

Large segment of DNA acquired from another species through horizontal gene transfer; an example is a pathogenicity island.