Flashcards in M&R Deck (78)
Where are phospholipids synthesised?
Endo plasmic reticulum
What 4 molecules can make the head of phospholipids?
Choline, Amines, Amino Acids and Sugars
Normal length of fatty acids in phospholipids?
Name 2 proteins that are integral eyrthrocyte proteins and 2 that are peripheral. How are peripheral proteins attached?
Integral: Ban 3 -anion exchanger and Glycophorin A
Peripheral: spectrin, actin (make actin-spectrin network) and adducin, ankyrin, band 4.1 ( adapter proteins which bind to ban)
Spectrin formed from a2 and b2 subunits (rods) and bound via an adaptor called ankyrin.
How long are membrane spanning domains
18-22 amino acids
What is the role of ribophoryns?
Anchor ribosome to ER
How may the energy for active transport be found?
Concentration gradient of transported substance/ the electrical potential across the membrane (secondary)
What is he difference between carrier and channel proteins?
Channel proteins allow specific ions to pass through them.
Carrier proteins usually move molecules by binding to them, changing shape and releasing it the other side of a membrane.
What does NCX exchange?
3Na for 1Ca
What protein can mediate alkali extrusion
Cell shirking/ swelling questions
Why do phospholipids form a bilayer instead of micelles?
Due to 2 FA chains.
4 types of motion of a phospholipid
Flexion (vibration) and intra chain motion e.g. Kink formation.
What are the functions of cholesterol in a cell membrane?
Reduces endothermic phase transition (prevents changes of state)
Bonds via OH to hydrophilic heads (C=O)
Increases fluidity - reducing phospholipid packing.
Decreases fluidity - reduces phospholipid chain motion.
What is freeze fracture.
Lipid bilayer frozen in ice.
E fracture extracellular.
P fracture is in cytosol.
Shows membrane proteins either side.
How can membrane proteins move?
NO FLIP FLOP
** Tend to spread out into cholesterol poor areas (called lipid mediated effects)
**may be restrained by associations
What is the purpose of a hydropathy plot?
Shows the charges of amino acids of a protein e.g. Transmembrane domains.
Briefly how are membrane proteins orientated?
If no signal peptidase. Hydrophilic NH3 terminus stays on outside (often accompanied by hydrophobic domain) and COOH terminus is synthesised through ER and into the lumen.
If signal peptidase then NH3 is created on the luminal side and COOH is in the cytosol (split in two).
What is a molecule called which has both hydrophobic and hydrophilic regions?
What is a plasmalogen?
A non classical phospholipid
What is Sphingomyelin?
Only phospholipid not based on glycerol.
Resembles other phospholipids in a membrane.
What is the difference between cerebrosides and gangliosides?
Both are glycolipids.
Cerebrosides contain a monomer head.
Gangliosides contain a oligosaccharides head.
What can be the result in a deficiency of erythrocyte cytoskeleton?
What protein is most important in allowing ionic movement to establish the resting membrane potential?
Voltage insensitive K+ channels
The nicotinic acetylcholine receptors are permeable to which main ions?
Na, K, Ca
The glycine channel is permeable to which ions?
Which can permeate a lipid membrane? H20, urea, glycerol?
All because they are small molecules
What is a P-type ATPase?
ATP phosphorylates an aspartate to produce energy for active transport e.g. Na/K ATPase
Intra and extracellular Na?