lipids and membranes Flashcards
saturated conformation
straight conformation = lowest energy
which fatty acids melt at higher temperatures
saturated
is there free rotation around a double bonds
no
why are triacylglycerols even less soluble in water than fatty acids
no charged carboxylate
higher % of long, saturated chains means
higher melting temperature
waxes make up
long chain + long chain alcohol
glycerophospholipids
two fatty acids and phosphate head and polar head group
sphingolipids
sphingosine + fatty acid + head group
also has head group
2nd carbon of sphingospine
nitrogen + fatty acid
ceramide
sphingolipid
what are constituents of membranes
spingolipids + glycerophospholipids + cholesterol
what do sterols form
rafts
what does sterol influence
Tm (melting temp)
micelles
individual units are wedge-shaped
vesicle
individual units are culindrical, has bilayer
why do bilayers “roll up”
bilayer is unstable unless the edges also have their interactions satisfied so it rolls up
cholesterol is _____ specific
animal
what composes a large percentage of membrane
protein
sterols are highly _____ related molecules
structurally
what else are sterols used for
testoterone, estrogen
there’s more cholesterol in the _____ membrane
plasma
paracrystalline state
frozen like a solid, low temp
fluid state
highly fluid, high temp
high saturated fatty acids means what abt temp
high temp
high unsaturated fatty acids means what abt temp
low temp
uncatalyzed lateral diffusion is
very fast
moving FA from outter leaflet to inner leaflet (transbilayer diffusion) is very ______
slow
why is transbilayer diffusion not favorable
moving hydrophilic head thru hydrophobib tails is unfav
flippase requires
ATP
scramblase does need ATP
no
scramblase which direction
bidirectional
flippase which direction
unidirectional
flippases keep choline containing lipids in the _______ leaflet
extracellular
flippases keep phosphatidylserine in the _______ leaflet. if on other side, could trigger apoptosis
intracellular
______ rigidifies and thickent ths bilyaer by forcing nearby phospholipids acyl chains to be more extended
cholesterol
lipid rafts contain
cholesterol, sphingolipids
rafts are
signalinging centers
are glycerophospholipids in rafts
no
defining characteristic of lipids
insoluble in water
lipid roles
membrane structure
energy storage
usual number of carbons in common fatty acids
even
draw tag
do it
draw pl
do it
draw FA
do i t
why is lauric acid more highe enrgy density than sucorse
energy stored in reduced carbon
sucrose more oxidized
why are TAGs good energy stores
- higher energy density per gram
- no need for hydration
why are waxes biological sealent
impervious to water
how are micelles formed
detergents
example of miclle detergent
SDS
what forms vesicles
glycerophospholipids or sphingolipids
is there sterol in bacteria
more cholesterol in what type of membrane
plasma
purpose of flippases and floppases
keep lipids on right side of the leaflet
ex: phosphatidylserine on intracellular side
what does cholesterol do to the bilayer
rigidifies and thickens
without cholesterol, smakll change in temperature can
elicit big change in membrane fluidity
with cholesterol, small change in temperature
smaller change in fluiity
cholesterol purpose
buffer, temper how fluid the membrane can become
