01:119:115 Lecture Notes - Lecture 2: Ammonia, Nitrification, Cytoplasm
15 Oct 2017
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Origin of life: chemical evolution hypothesis (3 steps, life was heterotrophic -> photosynthetic autotrophs -> aerobes, aerobes organisms that utilize oxygen. Human body with 70 trillion cells. (eukaryotic: 700 trillion bacteria in and around body. Maintains shape of cell: cocci = balls/sphere, diplococcus ^2, streptoccocus chain, stephylococcus -clump, bacilli - rods, spirillium - (rigid, spirochete (flexible, prevents cell from bursting in a hypotonic environment. Does not prevent plasmolysis in hypertonic environment (figure 7. 12) Polymer structure sugars crosslinked by short polypeptides. Not in eukaryotic cell walls (some eukaryotes do have cell walls likeplants and fungi: plants cellulose, fungi chitin. Surrounds cell wall, composed of polysacs and proteins. Fimbrae shorter + more numerous than phili. Common motility structure found in bacteria, archaea, eukaryotes. In prokaryotes flagella is 1/10 as wide and not covered by pm: different molecular compositions, different propulsions (movement) Bacteria vs archaea: similar size, similar propulsion mechanism, different composition.
