1928 Transformation

Transformation

• Frederick Griffith showed,
• before we knew about DNA,
• that live bacteria could incorporate genes
• from dead bacteria,
• transforming themselves
• from a nonvirulent form
• into a form that could kill mice.

Horizontal gene transfers

• Mitochondria, organelles
• that provide energy for all our cells,
• could originally have been bacteria
• incorporated by early eukaryotes.
• Plastids in plants and algae
• that perform photosynthesis
• or other chemical synthesis for energy
• could originally have been cyanobacteria.
• The genomes of mitochondria and plastids
• are circular,
• as are the chromosome of prokaryotes.

Competence

• Griffith called it “competence,”
• but it’s more like susceptibility.
• Challenge a creature by starving it
• or cramming it together with others
• and in its weakened state
• it more readily admits a foreign genome.
• This discovery is significant
• for genetics and evolutionary theory.

One on one

• One on one
• who’s to say
• promiscuity
• doesn’t pay.