Cell Membranes Flashcards
what are 5 functions of cell membranes
defines boundary of cells and cellular oganelles
separates cellular environment from extracellular environment
separates aqueous regions of different compositions within cells
controls the movement of molecules between different environments
regulates signal transduction
what is the structure of phospholipid
hydrophilic head
hydrophobic tail
describe structure of hydrophilic head
glycerl
phosphate
choline
what is unique feature of hydrophobic tails
at least one tail has 1 cis-double bond
what is the structure of a phosphogylceride
2 fatty acid tails
3 carbon glycerol molecules
1 phosphate molecule
common head group
what are the 3 common head groups on a phosphoglyceride
ethanolamine- neutral
serine- negative
choline- neutral
what mass percentage do phosphoglycerides make up in membranes
50%
what is the structure of sphingomyelin
18 carbon sphingosine molecule(instead of glycerol)
one fatty acid chain is within sphingosine and theres another fatty acid chain
what are the common head groups for sphingomyelin
phosphate and choline
what percentage of lipid mass do sphingomyelin account for
50-60%`
what is the remaining mass in membrane made up of
sterols
describe 3 points about membrane lipid composition
no symmetry
cant flip flop across
can move freely in their layer
what is a lipid microdomain
only exists for few microseconds
cholesterols appear denser
brings affecters and receptors together for signalling or apart for no signalling
what are two examples of alpha-helical transmembrane proteins
glycophorin A
bacteriorhodopsin
describe glycophorin A
single pathway protein in membrane - heavy in blood cells
describe bacteriorhodopsin
multipath transmembrane protein
helices can allow channels to be opened/closed and control entry/exit
what are beta barrel transmembrane proteins
found in mitochondria and chloroplasts
stiffer and more fixed than alpha
not in plasma membrane
how are lipid anchored proteins attached
via lipid modifications
what are the three anchors for lipid anchored proteins
myristol
palmitoyl
farmesyl
describe fluorescent recovery after photobleaching
bleach with laser beam
watch it recover
can only recover by fluoresed lipids moving into area
what does fluorescent recovery show
use technique to work out dynamics
test recovery time/ability
