01:119:115 Lecture Notes - Lecture 2: Crystal Violet, Gram Staining, Bacterial Capsule
18 Jul 2016
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Prokaryotes thrive almost everywhere, including places too acidic, salty, cold, or hot for most other organisms. Most prokaryotes are microscopic and numerous: there are more in a handful of fertile soil than the number of people who have ever lived. Prokaryotes are divided into two domains: bacteria and archaea: the tree of life describes three domains to include eukaryotes. Concept 27. 1: structural and functional adaptations contribute to prokaryotic success. 3 most common shapes are spheres (cocci) fig 27. 2: diplococcus- group of 2, streptococcus- chain, staphylococcus- clump. Cell wall maintains cell shape, protects the cell and prevents it from bursting in a hypotonic environment. Contain peptidoglycan: sugar polymers cross-linked by polypeptides: eukaryotes cell walls are made of cellulose or chain, archaea contain polysaccharides. Gram stain classifies bacteria by cell wall composition (fig 27. 3): Gram-positive: simple cell walls containing thick peptidoglycan e. g. staphylococcus aureus (penicillin sensitive)
