The Cell Membrane Flashcards

1
Q

What are the general functions of cell membranes?

A

Continuous, selective permeability barrier
Control of enclosed chemical environment Communication
Recognition signalling molecules
Signal generation in response to stimuli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Examples of signalling molecules?

A

Adhesion protein

Immune surveillance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the composition of membranes in dry weight?

A

40% lipid
60% protein
1 to 10% carbohydrates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the ranges of fatty acid chains?

A

C14-C24 and C16-C18

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Examples of phospholipid head groups?

A

Choline
Define
Ethanolamine
Inositol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a sphingomyelin?

A

(Sphingolipids) it’s the only other phospholipid with a phosphate in the membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is a liposome? Their use?

A

An enclosed structure.

Delivery of drugs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are cerebrosides and gangliosides?

A

Cerebrosides- head group sugar monomer Gangliosides- head group oligosaccharide (sugar multimers)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the different types of phospholipid motion?

A

Flexion
Rotation
Lateral diffusion
Flip-flops

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the influences of cis double bonds in the bilayer structure?

A

Unsaturated hydrocarbons chains with sis double bonds reduce phospholipid packing increasing the fluidity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the structure of cholesterol?

A

Polar had a group, rigid planar steroid ring structure. Non polar (flexible) hydrocarbon tail. Hydroxyl head group

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the significance of the hydrogen bond between the

A

Reduces mobility and motion therefore reducing the fluidity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the paradoxical effect of cholesterol?

A

Reduced phospholipid chain motion reduces fluidity.

Reduced phospholipid packing increases fluidity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are lipid rafts?

A

Dynamic cholesterol rich structures comprised of sphingolipids with saturated fatty acid chains and tightly integrated cholesterol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the function of lipid rafts?

A

Signalling scaffolds which allows dimerisation of signalling pathways

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the two types of evidence for proteins in membranes?

A

Functional- facilitated diffusion

Biochemical- freeze fracture and gel electrophoresis

17
Q

What is freeze fracture and two faces?

A

Fracturing a crystal with a knife, between two membrane lamella. P fracture face and E fracture face.

18
Q

What is SDS?

A

A detergent that coats all proteins with a negative charge so they move in the same direction during a gel electrophoresis.

19
Q

What are the three modes of mobility of proteins in the bilayer?

A

Confirmational change
Rotational
Lateral

20
Q

Why can’t proteins flip-flop?

A

The amount of hydrophilic structure that is exposed to the aqueous environment is too big and too energetically unfavourable to flip across the membrane

21
Q

What are the restrictions of proteins in the bilayer?

A

Membrane protein associations
Association with extramembranous proteins
Lipid mediated effects

22
Q

What are the two main membrane proteins and their features?

A

Peripheral they have electrostatic and hydrogen bonds interactions, removed by changes in pH or in ionic strength

Integral they interact extensively with hydrophobic domains of the bilayer, removed by agents that compete for nonpolar interactions

23
Q

What are transmembrane polypeptide composed of?

A

Small, hydrophobic, polar and charged amino acids R groups. Alpha helical domains.

24
Q

What is a hydropathy plot?

A

To check for membrane proteins

25
Q

What does the membrane protein topology look at?

A

Orientation in the bilayer

26
Q

Purpose of an SDS page of erythrocyte membrane?

A

To distinguish between peripheral and integral proteins

27
Q

What are the key features of the erythrocytes cytoskeleton?

A

Transmembrane protein anchors

Spectrin lattice adhered through attachment proteins

28
Q

What are the two types of haemolytic anaemia and their features?

A

Hereditary spherocytosis- spectrin depleted by 40 to 50% so less resistance to lysis

Hereditary elliptocytosis- defect in spectrin so can’t form heterotetramers