Mo - Genetic variation of bacterial pathogens Flashcards
What are the three ways of horizontal gene transmission for bacteria? (simple) (3)
Transformation, conjugation, transduction
What does the ‘transformation’ way of Horizontal Gene Transmission mean? (simple)
When a bacterium dies, there are free DNA pieces laying around for other bacteria to pick up and integrate in their own genome
What does the ‘conjugation’ way of Horizontal Gene Transmission mean? (simple)
Small versions of chromosomes are passed on from bacterium to bacterium
What does the ‘transduction’ way of Horizontal Gene Transmission mean? (simple)
Using phages, they put their genetic load into the chromosome of the bacterium.
Gene acquisition is (less/more) frequent than gene replacement
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What is genetic headroom? (meaning)
The amount of dispensable information in the genome
What does genetic headroom mean for the bacterium? (what does it determine)
It determines genetic flexibility
What are pathogenicity islands?
Clusters of contiguous genes, acquired by horizontal gene transmission
What are the three ways of determining if HGT has happened? (simple) (3)
GC content, Codon usage, Gene order (synteny)
If there is (less/more) GC content and (less/more) codon frequency bias, those are signs for alien genes, and are signs that thus HGT has happened.
Less GC content, more codon frequency bias
How can one determine that HGT has happened by looking at codon usage?
By looking at the frequency for making a certain protein
What is the difference between an open and a closed genome in regards to HGT?
If you keep finding more genes (with HGT), then it’s an open pangenome. If not, then it’s a closed pangenome.
If two bacteria share 70% the same DNA identity as well as 98% 16S rDNA, what does that mean?
The bacteria are the same species
How do intracellular bacteria get genetic diversity? (simple)
Clonal descent
What is clonal descent? (explain, simple)
In clonal descent the gene loses pieces of DNA to become different strains
