II. Genetic Diversity

A. Rapid reproduction plus mutation B. Genetic Recombination

Rapid reproduction plus mutation

• What promotes genetic diversity, ex. E coli in human intestine

• 1 in 10 million chance for mutation during DNA replication

• 2x 10^10 cells in one intestine

• Around 2000 mutation/ generation in that gene

• 4,300 genes in E. coli

• Thus because reproduction rate is so high and rapid, one mutation can infect the entire host

• Significance

  • Rare on per gene basis

  • Short generation and large population -> increase in genetic variation

  • High diversity -> rapid evolution -> better adapted

Evolution Experiment

• 12 E. Coli populations 

• Many interesting results 

  • Many mutations but when adapted to environment fitness maintained, amount of mutations level and become more rare

Genetic Recombination

• Combining DNA from 2 sources

• Sexual eukaryotes- meiosis + fertilization -> new allele combinations 

• Prokaryotes - no meiosis

• Can still recombine, even between different species

Horizontal gene transfer in prokaryotes

1. Transformation

• Foreign DNA incorporated as plasmids or into the bacterial genome (Griffith experiments)

2. Transduction

• Phages transfer bacterial DNA, generally same species of bacteria, (bacteriophage interests DNA into bacteria, recombination takes palace, genome from one bacteria incorporated to other, passes to next gen, not lysogenic)

3. conjugation

• Direct transfer of genetic material fro one cell to another

• Involved F(fertility) factor- genes required for conjugation, often on a plasmid

• Cells that have F+ cell

• Required for production of pili (  )