Membrane Structure + Permeability

Question 1

What is permeability affected by?

Answer 1

-temperature
-solvent concentration

Question 2

How does temperature affect permeability?

Answer 2

-proteins + lipids are affected by temp
-higher temp = lipids more fluid = reduces effectiveness of cell membrane
-diffusion takes place faster speed at high temp

Question 3

What happens at certain temperature to the membrane?

Answer 3

-certain temp - proteins start to denature - disrupts membrane structure
=substances pass through freely
(Irreversible)

Question 4

How does solvent concentration affect permeability?

Answer 4

-organic solvents - increase permeability
-as they dissolve lipids in membrane
-loses its structure

Question 5

Method to practical investigating factors affecting membrane permeability

Answer 5

1. Scalpel - cut 5 equal cubes of beetroot
2. Cork borer cut to same length
3. Rise cubes - remove any pigment
4. Add to diff test tubes - all same v of water
5. In water bath at diff temps - same time
6. Remove beetroot
7. Colorimeter- measures how much light is absorbed as it passes through liquid
8. Higher absorbance = more pigment released = greater permeability

Question 6

Results from practical into factors

Answer 6

-as temp increase - so does permeability
-phospho move more
-not tightly packed anymore
-increases permeability

Question 7

Limitations of practical into factors affecting permeability

Answer 7

-cuvettes - differ in thickness
-thicker = absorb more light
-use the same for every reading
-beetroot may not be same size and shape
-some parts have more pigment than others