MCB 3020 Lecture Notes - Lecture 6: Plasmolysis, Sodium Chloride, Penicillin Binding Proteins
Document Summary
Cellular growth and determination of cell shape: determined by peptidoglycan synthesis in bacteria. Penicillin binding proteins (pbps) link peptidoglycan strands and catalyze controlled degradation for new growth. Autolysins pbp enzymes that degrade peptidoglycan at site new units added. Cell wall growth and cell shape determination: vibrio (comma-shaped bacteria) Crescentin intermediate filament homologue localizes to short, curved side of cell. Influences of environmental factors on growth: physiology and adaptation to environment, most organisms grow in fairly moderate environmental conditions, extremophiles. Grow under harsh conditions that would kill most other organisms. Solutes and water acidity: changes in osmotic concentrations in the environment may affect microbial cells. Membrane shrinks from the cell wall (plasmolysis) may occur. Microbes adapt to changes in osmotic concentrations: reduce osmotic concentration of cytoplasm in hypotonic solutions. Mechanosensitive (ms) channels in plasma membrane allow solutes to leave. Increase internal solute concentration with compatible solutes to increase their internal osmotic concentration in hypertonic solutions.
