Cell membrane and organelles Flashcards
Fluid mosaic model
- phospholipid (and protein) molecules moving laterally
- presence of embedded proteins scattered in the membrane
effect of high temp on cell membrane
effect on phospholipids:
- high temps result in disruption of HI between phospholipids
- thus causing membrane to become too fluid (i.e. more transient gaps)
- (specific membrane property) and causing cell membrane to be ineffective as a barrier
effect on proteins:
- high temps result in denaturation (i.e. loss of 3d conformation) of proteins
- through breakage of H bonds, ionic bonds and HI
- (specific protein function) thus resulting in non-functional transport protein / no more enzyme activity / …
protein synthesis at rER
- bound ribosomes on rER synthesise polypeptide
- synthesised polypeptide is then passed through rER membrane
- and into the rER lumen for folding and packaging into vesicles
- transport vesicles containing folded polypeptide pinch/bud off rER
protein synthesis at Golgi body/apparatus
- modification/glycoslylation of protein,
- which is then packaged/sorted at the cell surface for secretion
- bud off as secretory vesicles,
which then move towards and fuse with plasma membrane,
resulting in the release of contents via exocytosis
process of exocytosis
- (a) movement of vesicles to the cell surface membrane
(b) and fusion of membrane of vesicle with cell surface membrane - thus emptying vesicle contents into extracellular region
how nutrient availability affects processes
(e.g. cell division)
- glucose
-> required for aerobic respiration to release ATP
-> used as energy required for process - essential amino acids,
which cannot be produced by cells and thus must be taken up from envt
-> to synthesise important proteins needed for process