plasma membrane structure

Question 1

describe the fluid mosaic model?

Answer 1

fluid= molecules move around
mosaic = The scattered pattern produced by the proteins within the phospholipid bilayer l

Question 2

describe the phospholipid bilayer?

Answer 2

hydrophillic heads - attracted to water
hydrophobic tails - repelled by water

Question 3

what is the effect of cholesterol on membrane structure?

Answer 3

• restricts lateral movement of other molecules in the membrane

Question 4

why is cholesterol useful for the membrane structure in HIGH TEMPERATURES?

Answer 4

• at high temperature
• makes membrane less fluid
• prevents water and dissolved ions leaking out of the cell

Question 5

why is cholesterol useful for the membrane structure in LOW TEMPERATURES?

Answer 5

• Cholesterol molecules sit in between the phospholipids
• preventing them from packing too closely together
• prevents membrane freezing and cracking

Question 6

what is the role of cholesterol for membranes?

Answer 6

• regulates the fluidity of the membrane

Question 7

why do membranes become less fluid?

Answer 7

1) increase in saturated fatty acid chains
- chains pack closely together so high intermolecular forces
-
2) lower temperature
- molecules have less energy
- so not moving as freely, structure is more tightly packed

Question 8

why do membranes become more fluid?

Answer 8

1) increase in unsaturated fatty acid chains
- chains are bent
- so less tightly packed
- less intermolecular forces

2) higher temperatures
- molecules have more energy
- so move more freely, structure is less tightly packed