Lecture 3 Flashcards
(14 cards)
What are membranes composed of by dry mass
40% lipid
60% protein
1-10% carbohydrate
However membranes are hydrated so 20% of their weight is water
What does amphiphatic mean?
The molecules has both a hydrophobic and hydrophilic portion
What does phosphotidylcholine consist of
Two fatty acids
A glycerol
A phosphate and a choline
Phospholipids can have a range of polar head groups such as choline, amines, amino acids and sugars
What does a phospholipid consist of?
Two fatty acids a glycerol and a polar head group. Can be phosphate or choline etc
What causes a cis double bond and kink in a fatty acid?
Unsaturated fatty acid
What is a glycolipid?
Where phosphate head group replaced by sugar
What is the only phospholipid that doesn’t have a glycerol backbone?
Sphingomyelin
What is the difference between a cerebrospinal and a ganglioside?
Cerebrospinal is a glycolipid with one sugar molecule and a ganglioside has an oligosacchsride head group with multiple sugar units
What is a liposome?
Like a circular lipid bilayer. Can be used to transport drugs.
What is the difference between phospholipid motion and cholesterol motion?
Cholesterol cannot flip flop
What is the influence of cis double bonds on membranes?
Kink prevents packing and keeps environment dynamic.
Describe cholesterol structure?
Has a polar head group with a hydrophobic and rigid planer sterol ring and a non-polar hydrocarbon tail
Why is cholesterol important for membranes?
At low temperatures it prevents packing because of its rigid sterol ring.
At high temps it prevents too much fluidity as rigid sterol ring prevents too much phospholipid movement.
Cholesterol effects on bilayer?
Reduces phospholipid packing and increases fluidity at low temperatures. Reduces phospholipid chain motion and so reduces fluidity at high temperatures
