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0

Where are phospholipids synthesised?

Endo plasmic reticulum

1

What 4 molecules can make the head of phospholipids?

Choline, Amines, Amino Acids and Sugars

2

Normal length of fatty acids in phospholipids?

C16 C18

3

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.

4

How long are membrane spanning domains

18-22 amino acids

5

What is the role of ribophoryns?

Anchor ribosome to ER

6

How may the energy for active transport be found?

ATP hydrolysis
Concentration gradient of transported substance/ the electrical potential across the membrane (secondary)

7

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.

8

What does NCX exchange?

3Na for 1Ca

9

What protein can mediate alkali extrusion

Anion exchanger.

10

Cell shirking/ swelling questions

J

11

Why do phospholipids form a bilayer instead of micelles?

Due to 2 FA chains.

12

4 types of motion of a phospholipid

Flexion (vibration) and intra chain motion e.g. Kink formation.
Flip-flop
Rotation
Lateral diffusion

13

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.

14

What is freeze fracture.

Lipid bilayer frozen in ice.
Split.
E fracture extracellular.
P fracture is in cytosol.
Shows membrane proteins either side.

15

How can membrane proteins move?

Conformational change.
Rotation
Lateral diffusion
NO FLIP FLOP
** Tend to spread out into cholesterol poor areas (called lipid mediated effects)
**may be restrained by associations

16

What is the purpose of a hydropathy plot?

Shows the charges of amino acids of a protein e.g. Transmembrane domains.

17

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).

18

What is a molecule called which has both hydrophobic and hydrophilic regions?

Amphipathic

19

What is a plasmalogen?

A non classical phospholipid

20

What is Sphingomyelin?

A plasmalogen.
Only phospholipid not based on glycerol.
Resembles other phospholipids in a membrane.

21

What is the difference between cerebrosides and gangliosides?

Both are glycolipids.
Cerebrosides contain a monomer head.
Gangliosides contain a oligosaccharides head.

22

What can be the result in a deficiency of erythrocyte cytoskeleton?

Haemolytic anaemia.

23

What protein is most important in allowing ionic movement to establish the resting membrane potential?

Voltage insensitive K+ channels

24

The nicotinic acetylcholine receptors are permeable to which main ions?

Na, K, Ca

25

The glycine channel is permeable to which ions?

Cl

26

Which can permeate a lipid membrane? H20, urea, glycerol?

All because they are small molecules

27

What is a P-type ATPase?

ATP phosphorylates an aspartate to produce energy for active transport e.g. Na/K ATPase

28

Intra and extracellular Na?

I:12mM
E:145mM

29

Intra and extracellular K?

I:155mM
E:4mM