4.1 structure of the cell-surface membrane Flashcards
1
Q
describe the (5) different substances of the cell-surface membrane.
A
- phospholipid bilayer: hydrophilic phosphate head & hydrophobic fatty-acid tail
- proteins (extrinsic, intrinsic, channels / carrier)
- glycolipids
- cholesterol
- glycoproteins
2
Q
describe the advantages of the phospholipid bilayer.
A
- allow lipid-soluble molecules to pass through
- prevent water-soluble substances to pass through
- flexible and self-sealing
3
Q
describe the uses of extrinsic & intrinsic proteins on the cell-surface membrane.
A
- extrinsic protein: on 1 side of bilayer only, acts as mechanical support or as cell receptors with glycolipids
- intrinsic protein: spans through both bilayer, acts as protein channels & carrier proteins
4
Q
describe the role of cholesterol in the cell-surface membrane.
A
- adds strength to membranes
- prevent leakage of water (very hydrophobic)
- makes membrane less fluid at high temperatures
5
Q
describe the role of glycolipids in the cell-surface membrane.
A
- acts as recognition sites
- maintain stability
- help cells to attach & form tissues
6
Q
explain what the fluid-mosaic model meant.
A
fluid: flexible phospholipid molecules could move relative to one another
mosaic: proteins embedded varies in shape, size and pattern
7
Q
what molecules doesn’t diffuse through the cell-surface membrane?
A
- insoluble in lipids
- large-sized
- polar / electrically charged