MCO test 3 Flashcards
membrane function
semipermeable barrier
detects and interprets changes in extracellular environment
anchorage for proteins and cytoskeleton
lipid structure
diverse
defined by hydrophobicity rather than structure
soluble in organic solvents
phospholipids
amphiphilic/amphiphatic
polar = hydrophillic
fatty acids are hydrophobic
ampiphatic
both properties
membrane typically contains _ lipids
109 lipids
_____ lipid molecules per __ of bilayer
5 x 10^6 per 1 micrometer squared
internal membrane modifications done in ER only found on ___ side
exo
micelle liposome
hydrophobic
fatty acids
terminate with carboxylic acid group
long hydrocarbons (14-24C) 16/18 most common
saturated fatty acids means no
double carbon bond
so straight chain
C:D
number of carbons to numbers of double bonds
C=C
introduces kink in chain causes irregular packing (leading to lower melting point) OR more fluidity
essential fatty acids must be
Obtained through diet
smedley-maclean
Arachnoid acid 20:4
synthesised from clinic acid precursor for eicosanoids
also important for phospholipid bilayer
plays important role in inflammation
(diagram)
phospholipids can be modified by
ester bonds between phosphate groups
common head groups
have biological functions
phosphaldyl choline and phoshatidlynositol can be cleaved inositol and choline are important signalling molecules
PLC is activated process
1)signal transmits to phospholipase (PLC) only some pathways depend on phosphatidylserine other membrane proteins important
2)inositol phosphate is cleaved and transmits signal into cell
sphigomyelin
sphingosine with a fatty acid and hydrocarbon chain andcholien attached
choline
in myelinated axons signal transduction apoptosis
glycolipids
-sugar containing lipids instead of P group
-can be more than one sugar unit
-dereived from sphingosine not glycerol
-sugar always on outside of cell
cholesterol
-modified steroid
-cholesterol 4 hydrocarbons only steroid ring is in membrane
glycolipids role
for immune responses
cell recognition
attachments lipids
importance of membrane fluidity
-lipids diffuse laterally
-proteins not involved in anchoring also diffuse
-proteins need to transmit signals
-transport across by diffusion or via transporter
-vesicles need to bud off and fuse
measuring rate of lateral diffusion in membrane
-membrane with flurophobes
-intense light bleaches flurophobes
-rate of diffusion of flurophobes can be measured