chapter 13- mechanisms of microbial evolution Flashcards
What is evolution?
change in allele frequencies over time
Mutation
random changes in DNA
What are the 4 types of mutations?
substitutions, deletions, insertions and duplications
What does recombination mean?
breaking and rejoining of DNA segments
What can recombination achieve?
- reassortment of genetic material
- can be homologous (requires similar segments) or non-homologous (high similarity)
Evolutionary selection
defined by ability of organism to produce progeny and contribute to genetic makeup (fitness)
What are the 2 different types of mutations?
- deleterious: mutations decrease fitness (get removed by natural selection)
- beneficial: mutations increase fitness (favoured by natural selection)
Genetic drift
random process causing gene frequencies to change overtime resulting in evolution
What is experimental evolution?
using experiments with microbes to investigate evolutionary process
Why are microbes used?
they grow very rapidly and can be preserved through freezing.
What is an example of a long term experimental evolution?
E. Coli
- running since 1988, grown aerobically, within defined media (glucose and citrate)
- dramatic increase in fitness, then slowed
- strains evolved, marked with natural marked
- E. Coli couldn’t utilize citrate, throughout time, mutations allowed that evolution to be possible.
Homologs
genes descend from common ancestral sequence
Orthologs
sequences have diverged due to a speciation event
Paralogs
homologous sequences share common ancestors due to gene duplication events
Gene families
groups of gene homologs.
