Lecture 2.12 Notes

Lecture 2.12 Notes - Environmental Effects on Microbial...

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Environmental Effects on Microbial Growth Temperature: Crucial environmental factor effecting growth and survival Each organism has its own cardinal temperatures, which vary widely among different organisms: o Minimal temperature – gelling of membrane, inability to maintain pmf o Optimal temperature –generally nearer the max than min o Maximum temperature – denaturation of key proteins/structures Temperature effects on cellular machine functions Cytoplasmic membrane o Membrane integrity destroyed at high temps o Membrane fluidity “frozen” at low temps Protein/enzyme – structure/function o Proteins denatured at high temps o Enzyme function compromised at low temps Factors affecting cardinal temperatures: effects of temperature on membranes Fatty acid composition of cytoplasmic membrane o Fully saturated fatty acids tightly packed fatty acids more stable, less fluid membrane o Unsaturated fatty acids fatty acids less tightly packed more fluid membrane Butter vs olive oil Factors affecting cardinal temperatures: effects of temperature on protein structure Review: what drives protein folding? Secondary structures of proteins: certain motifs of protein structure found in many different proteins Mediated by hydrogen bonding of amino groups and carbonyl groups of peptide backbone o α-helix – hydrogen bonds between nearby amino acids o ß-sheet – hydrogen bonds between distant amino acids Ultimate folding of proteins involves many complex considerations Certain R-groups can interfere with ability to form α-helix or ß-sheet
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Lecture 2.12 Notes - Environmental Effects on Microbial...

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