3 Bacterial genome evolution

Transient

DNA sequence is not changed, short-term/temporary expression of a gene

Heritable

change in DNA sequence

(a mutation and HGT is a heritable change in DNA sequcne)

Core genome

present in all members of a species, for E. coli ~2k genes

Pan genome

all genes found in members of a species, for E. coli ~75k genes

What enables for the classification of two bacterial strains being the same species?

strains of a species should show 95%≥ ANI (average nucleotide identity = average nucleotide identity of all orthologous genes shared between any two genomes)

What ar esome consequences of changes in genomes?

1. no phenotypic changes

2. changes in the function/folding/stability of proteins or RNAs

3. Changes in the expression of genes

4. loss of genes

5. acquisition of new genes (mutation or HGT)

what is recombinational gene loss

Recombination: breaking and joining of DNA in different combinations

Chromosomal rearrangements due to recombination between direct repeats on the same DNA molecule (intra-chromosomal recombination) result in deletions

IAD

Innovation, amplification, divergence

Orthologs

homologous genes encoding factors that perform the same function in different organisms

Paralogs

homologous genes encoding factors the perform different functions in one same organism

what is recombinational replication

recombination during replication between sister chromosomes can lead to 1 sister chromosome having an additional copy of a gene sequence.