Chapter 8 Flashcards
What are the two methods of genetic change
Mutation, Horizontal gene transfer
What is a mutation ?
A change in the nucleotide
sequence of DNA
What is a horizontal gene transfer
Genetic info is passed from
one living cell to another cell
of the same generation
* Ex. Plasmid transfer
How does a mutation occurs
Base substitution
(point mutation)
* A single nucleotide is
replaced by another
nucleotid
When DNA replicates
– results in a
substituted base pai
What is a Missense mutation.
When DNA is transcribed
and translated can result
in an incorrect amino acid
in the protein
what is Frameshift mutation
Changes the reading
frame of the mRNA
Almost always results
in a non-functional
protein.
What is Spontaneous mutation
Occur in absence of mutagens, due to occasional mistakes during
DNA replication
what is Induced mutation
Occur when DNA damaging agents cause changes in DNA
sequence – mutagens
* Ex: Radiation, some chemicals
mutations can result in?
- No effect on the protein (remains functional) – silent
mutation - A protein with a different amino acid sequence that may
have an altered function – missense mutation - Premature stop codon – Incomplete (truncated) protein,
usually nonfunctional – nonsense mutation.
GGA -> GGC
Glycine -> Glycine
AGC -> AGG
Serine -> Arginine
UGG -> UGA
Tryptophan -> STOP
What is a Plasmids
Self replicating, dsDNA
molecules
* Contain non-essential
genes
* ex. Genes for toxin
production
What is a F plasmids
F plasmids – Fertility factors
* Carry genes to make F pilus (or sex pilus)
* Involved in conjugation (transfer of genetic material between bacteria
What is a R plasmids
Resistance factors
* Carry genes for antibiotic resistance
What is a Vir Plasmids
Virulence factors
* Carry genes for toxin production.
Horizontal gene
transfer in bacteria has how many component
3
Horizontal gene transformation
Pieces of “naked”
DNA are taken up by
a bacterial cell
Recombination
* Can then be passed to progeny, and become a stable part of the
genome.
