gen bio - lecture 4: the origin of life

abiogenesis

how life emerged from non-living matter

process of abiogenesis (just list 4 steps)

1. abiotic synthesis (monomers)

2. formation of organic macromolecules (polymers)

3. formation of protocells

4. self-replication

abiotic synthesis (definition + requirements)

• formation of precursors required for life

• requirements:

  • little or no free oxygen (BC OXYGEN BREAKS BONDS/OXIDIZES)

  • source of energy needed

  • presence of chemical building blocks - CHON

  • time for molecules to react with one another

formation of macromolecules

• formation of polymers from monomers (protein or RNA)

• monomers polymerize on hot sand/rocks

  • process catalyzed by metal ions

formation of protocells

• lipids spontaneously form vesicles/containers

• protocells: aggregates of ABIOTICALLY produced organic molecules

  • NO MECHANISM OF HEREDITY

  • but exhibit electrical potential across surface, osmosis, homeostasis, and division

self-replication

• RNA = nucleic acid in photocells

• capable of self-replication and catalyzing protein synthesis

  • less stable than DNA which evolved later

heterotrophs

• anaerobic bacteria (no O2)

• use fermentation

cyanobacteria + O2 revolution

• photosynthetic autotrophs

  • use energy from sunlight, release O2

  • leads to a rise of atmospheric O2 = O2 revolution/apocalypse

    • kills off most organisms

eukaryotes

• arise from archaea + bacteria

• symbiotic relationship (mutually benefit from engulfing other cells like mitochondria and chloroplasts)