evolution + prokaryotes

• simple molecules with C/H/O/N underwent complex chemical rxns to form organic C-C compounds (triggered by energy source)
• synthesis of early compounds:

  • early atmosphere: thick with water vapor + very little oxygen + compounds from underwater volcanic eruption (CO2, CH4, H2, H2S, NH3)
  • earth cooled down --> water vapor condensed but left behind H2
• Oparin's bubble hypothesis:

  1. underwater volcanoes erupted and released gases as bubbles
  2. gases reacted and made simple organic molecules
  3. bubbles reached surface and popped
  4. simple molecules reacted to sunlight/lightning/energy source and turned into complex molecules
  5. more complex molecules fell into sea as raindrops to repeat process
• miller & urey experiment findings:

  • formation of organic compounds (including amino acids)
  • abiotic synthesis of organic molecules possible
• sequence of events:

  • abiotic synthesis of amino acids and nitrogenous bases
  • joining of two to form proteins and nucleic acids
  • packed into protocells (droplets with membranes that maintain internal chemistry different from surroundings)
  • origin of self-replicating molecules = inheritance
  • = RNA was the first molecule that jumpstarted biological evolution
• domains of life:

  • bacteria, archaea, eukarya
  • bacteria and archaea: prokaryotes
  • eukarya: eukaryotes
• structures seen in bacterial cells (prokaryotes):

  • plasma membrane
  • ribosomes
  • nucleoid (circular DNA)
  • periplasmic space
  • cell wall (peptidoglycan)
  • proteins
  • plasmids
• special features for prokaryotes:

  • gas vacuole
  • inclusion bodies
  • capsules and slime layers
  • fimbriae and pili
  • flagella
  • endospores
• prokaryote nutritional modes:

  • autotrophs: photo (light) and chemo (inorganic chemicals)
  • carbon source: CO2, HCO3
  • heterotrophs: photo (light) and chemo (organic compounds)
  • carbon source: organic compounds
• role of O2 in metabolism:

  • obligate aerobes (needs oxygen)
  • obligate anaerobes (oxygen is poisonous)
  • facultative anaerobes (oxygen can be used but not needed)
• archaea extremophiles:

  • halophiles: highly saline environments
  • thermophiles: very hot environments
• methanogens

  • swampy and marsh environments
  • produce methane
  • strict anaerobes
• bacteria:

  • no nuclear envelope
  • no membraned organelles
  • yes peptidoglycan cell walls
  • unbranched hydrocarbons in membrane lipids
  • 1 RNA polymerase
  • antibiotics inhibit growth
  • circular DNA
• archaea:

  • no nuclear envelope
  • no membraned organelles
  • no peptidoglycan cell walls
  • semi-branched hydrocarbons in membrane lipids
  • multiple RNA polymerase
  • antibioitc resistant
  • circular DNA
• eukarya:

  • yes nuclear envelope
  • yes membraned organelles
  • yes peptidoglycan cell walls
  • unbranched hydrocarbons in membrane lipids
  • multiple RNA polymerase
  • antibiotic resistant
  • helical DNA