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.