01:119:116 Lecture Notes - Lecture 2: Gram Staining, Dna Replication, Endospore
17 Jun 2020
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27. 1: structural and functional adaptations contribute to prokaryotic success. Peptidoglycan- most bacterial cell walls contain this- a polymer composed of modified sugars cross-linked by short polypeptides- this molecular fabric encloses the entire bacterium and anchors other molecules that extend from its surface. Archaeal cell walls contain a variety of polysaccharides and proteins but lack peptidoglycan. Gram stain- using this technique- scientists can categorize many bacterial species according to differences in cell wall composition. Gram positive bacteria have simpler walls with a relatively large amount of peptidoglycan. Gram negative bacteria have less peptidoglycan and are structurally more complex, with an outer membrane that contains lipopolysaccharides (carb bonded to lipids) Capsule- sticky layer of polysacc or protein that surrounds cell wall of many prokaryotes. Certain bacteria develop resistant cells called endospores when they lack an essential nutrient. The original cell produces a copy of its chromosome and surrounds that copy with a tough multilayers structure, forming the endospore.
