BIOL 224 Lecture Notes - Lecture 2: Osmolyte, Membrane Transport, Cytosol
Document Summary
Maintenance of volume is a critical problem faced by all cells. Cells must respond to swelling or shrinkage by activating specific membrane transport and/or metabolic processes. Cell volume is kept under control by transporting ions: gain of ions = swelling, loss of ions = shrinking, transport of ions = change in protein fx, system only works when change is small. Can sense and respond to volume changes of >3% Large changes in the levels of inorganic ions are incompatible with long-term normal protein fx. Exist in high [ ] in the cytosol of all organisms. Three classes: carbohydrates (e. g. sorbitol, amino acids and their derivatives (e. g. pro, methylamines (e. g. tmao) Two types: perturbing, disrupt metabolism via large shift in [ , ex: urea, compatible, does not affect protein fx, ex: gly, pro, inositol, and sorbitol, tmao, betaine, sarcosin, aa, taurin, glycerol, Produces and gets rid of organic osmolytes to maintain.
