cell membrane Flashcards
cell membrane function
generation of electrical signals
embedded proteins for sensing change
protection
have attachment sites as adhesion points
lipid bilayer contain…
proteins embedded/attached via non-covalent interaction
phospholipids consists of
amphiphilic molecule with non-polar hydrophobic tail and polar hydrophilic heads
lipid function in membrane
self organising and is around 50% of membrane mass
for spheres to make sealed compartment = enclosed cell
major phospholipids names
glycolipid phosphatidylemanolamine phosphatidylserine(-ve charge) phosphatidylcholine sphingomyelin sphingosime - used to build sphingomyelin
artificial liposomes
phospholipid bilayer in aq solution
cholesterol
polar head and non-polar tail
plants have sterol compound
fluidity of membrane when temp decreases
decrease in kinetic energy
phospholipids pack together
forming a crystalline state
fluidity of cholesterol when temp decreases
increase spacing between the hydrocarbons
increase in fluidity
flexion
movement of HC tails
fluidity of cholesterol when temp increases
pulls HC tails together
decreases fluidity - stabilise
fluidity of membrane when temp increases
kinetic increases
increase movement therefore packed less tightly
increase fluidity
lateral
movement of phospholipid within planes
rapidly
flip-flopping
movement of phospholipids between planes
more rare
Result of Cis double bonding
more difficult to pack
HC are shorter and more spread out
bilayer becomes thinner
lipid raft
more stable and move as a big unit
keep proteins associated together
contains more cholesterol and sphingolipids = move laterally
experiment of movement of proteins in membrane
human + mouse cell = hybrid
proteins monitored using antibodies and fluorescent dye
result of experiment of proteins
At 0 - dye is at either half of the cell
At 40 mins - dye is distributed
therefore protein is mobile in the membrane
