01:119:116 Lecture Notes - Lecture 2: Cyanobacteria, Clostridium, Phytoplankton
15 Mar 2017
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Document Summary
When did they first appear: 3. 5 billion years ago. How did we hypothesize that life first originated: prebiotic soup hypothesis. Three domains 2 are prokaryotes: bacteria, archaea, internal organization. Prokaryotes have: no membrane bound organelles, nucleoid, single haploid chromosomes, plasmids extra dna, cytosol, plasma membrane, enzymes for respiration and photosynthesis, cell wall. Cell wall functions: protection, maintain cell shape, prevents bursting in hypotonic solution. 2 step process stain wash to id bacteria: 1st crystal violet purple, 2nd safranin pink. Gram positive purple: thin peptidoglycan layer, does not hold violet, outer membrane of lipopolysaccharides (lps, thick cell walls hold violet stain. Is it more effective against gram positive or gram negative bacteria: motility. Some prokaryotes are motile: taxis random movement (positive vs negative taxis, flagella found in all domains but analogous. Prokaryotes vs. eukaryote flagella: prokaryotic 1/10th, no plasma membrane, mechanisms differ. H+ and the etc similar to the etc in respiration that drives atp synthase.
