Bacterial Genetic Variation Flashcards
What is a mutation?
Any change in the nucleotide sequence of an organism
Why do mutations occur?
Error in replication
Due to mutagens
What is a SNP - single nucleotide polymorphism?
A single base changes
SNPs can lead to missence. What is missence?
A change of amino acid
SNPs can lead to nonsense. What is nonsense?
A premature stop codon
SNPs can lead to sense. What is sense?
The removal of a stop codon
With mutations aside, bacterial chromosomes are very similar within a species. What distinguishes strains and phenotypes?
Variability
What types of bacterial variability are there?
Horizontal gene transfer Transformation Transduction Bacteriophages Pathogenicity islands Bacterial gene engineering
What is horizontal gene transfer?
Bacterial cells pulled together (conjugated) by fimbrae and pili
DNA foreign to host recombines into the hosts genome
This introduces an inheritable change in DNA
Why can’t plasmids replicate by themselves?
They lack some enzymes needed for replication
What is transformation? Where does the DNA come from?
The transfer of DNA from the environment into bacteria
DNA from nearby lysed cells or plasmids purposely added for genetic engineering
Bacteriophages outnumber bacteria 10:1. What are bacteriophages? What do they do?
Bacterial viruses
They encode genetic information into the hosts chromosome for their own replication
What is transduction?
When phages accidentally transfer non-phage DNA into capsid during replication
What is a pathogenicity island?
A series of genes in a pathogenic microorganism acquired by horizontal gene transfer
What do pathogenicity islands do?
Encode clusters of virulence genes for insertion into DNA
