Plasmalemma Flashcards
functions of plasmalemma
1 physical barrier
2 selective barrier
3communication
4 electrochemical gradient-sets up and maintains an electrical charge diff across lemma
5 keeps constant intracellular ionic content
6 bind cell to ecm via integrins
components of lemma
1 integral and peripheral proteins
2 two phospholipid layers
3 cholesterol
4glycocalxy
when is membrane more stable
when the phobic tails are in the middle away from the water and polar heads in contact with h20
why are phospholipid heads polar
due to the phosphate group
location and use of cholesterol
inserted at varying densities in phobic region restricting movement of the tails and thus modulate fluidity
glycocalyx structure and use
it Is the ogliosaccharide chains that extend outwrads from the glycoproteins and lipids and provides antigenic properties to cell
origin of trilaminar appearance of membrane
-due to fixation with osmium tetroxide. osmium binds with polar heads and glycocalyx forming 2 dark lines which enclose osmium free fatty acids ( 3rd lin )
what are intergral and peripheral proteins and location
- integral is a transmembrane protein which spans the entire membrane
- peripheral are found on one side of the bilayer usually the cytoplasmic side
other name for integral and reason
-multipass proteins as their chains span several times the memberane from side to side
what holds proteins in place in membrane
-interaction between phobic region and non-polar amino acids of protein
why are membrane assymetric
due to diff in distribution of proteins and other molecules across the 2 layers
fluid mosaic model
-proteins and other molecules are free to move laterally making a movable mosaic among the fluid lipid membrane
what limits fluidity of mosaic
-proteins and their cytoskeletal attachments or proteins which form subunits of large enzyme complexes are less mobile
lipid ratfs
-region in lemma where large protein complexes are found including high cholesterol and SFA reducing lipid fluidity and along with scaffold proteins allow proteins in raft to remail in close proximit and interact more efficiently
