Earliest life - when? In what?
- 3.4 billion years ago
- Found layered in rocks called stomatolites
Evidence of life
- From stomatolites
- Isotope ratios (depleted 12CO2 in limestone)
Models for early life (2)
- Prebiotic soup - small organic molecules arise abiotically (lightning=catalyst and lipids spontaniously organize into micelles)
- Metabolist Model - FeS catalyzes fixation of carbon = self-sustaining reaction (FeS still e- transport)
Why RNA first? (3)
- Has catalytic ability
- regulates gene expression
- synthesizes proteins
What is a ribnuclease p/ribozyme? What is it's structure?
- Ribonuclease P - is a ribozyme that acts as a catalyst in place of a protein
- formed by homologous base pairing within RNA molecule that gives fxnl 2ndary structure
During horizontal transfer what kind of gene is often transfered? What kind is not? Why?
- Operational genes transfer - fxn independantly of other cell components, bring added fxn, confer selective advantage
- Informational Genes (NOT)
Pathogenicity Island (3 characteristics and associated with?)
- associated with horizontal gene transfer
- large set of genes grouped together, transfer as a unit, and pathological genes