MGY377H1 Midterm: Study notes for midterm
Document Summary
Normal growth conditions based on human frame of reference. Any ecological niche outside this range considered extreme. Salt concentration of 0. 9: such life organisms called extremophiles. Four key factors: temperature, ph, water availability, oxygen. Cardinal temperatures for each organism: minimal temp, optimal temp, maximum temp. Below minimum temp, membrane gelling, transport processes so slow that growth cannot occur. Above maximum temp, protein denaturation, collapse of cytoplasmic membrane, thermal lysis. Classes: psychrophile optimal growth is fifteen degrees or less. survive in small pockets of water in ice, glaciers, glacial lakes, snowfields. grow in hot places, like soils with full sunlight, fermenting compost piles. Most organisms show range of two to three units. Classes: acidophiles grow at low ph. Internal ph is near neutral: neutrophiles grow best at ph 7, alkaliphiles grow best at high ph. use sodium gradient to drive transport, atp synthesis, motility. Water availability depends on water concent of environment and concentration of solutes.