Cell Membrane Flashcards
1
Q
List 5 functions of biological membranes
A
- Continuous, highly selective permeability barrier
- Control of the enclosed chemical environment
- Communication
- Recognition
- Signal generation in response to stimuli
2
Q
Describe the composition of the membrane
A
Varies with source of membrane:
- 40% lipid
- 60% protein
- 1-10% carbohydrate
N.B. membranes are hydrated structures, thus, 20% of total weight is water
3
Q
Describe the structure of a phospholipid
A
- Glycerol
- Attached to two fatty acids
- Attached to a phosphate
- Phosphate attached to head group
4
Q
What are some common phospholipid head groups?
A
- choline
- amines
- amino acids
- sugars
5
Q
What is the difference between a lipid micelle and a lipid bilayer?
A
- Lipid micelles are enclosed monolayers
- Lipid bilayers are more common
6
Q
What are the four ways in which a phospholipid can move in the bilayer?
A
- Flexion
- Rotation
- Lateral Diffusion
- Flip Flopping
7
Q
Why is a flip-flop movement rare?
A
-Energetically unfavourable for hydrophobic head to move through hydrophilic bilayer
8
Q
How may proteins move in the membrane?
A
- Conformational change
- Rotational
- Lateral
No flip flop, as it is energetically unfavourable
