5.2 Factors Affecting Membrane Structure

Question 1

How does temperature affect the cell membrane?

Answer 1

Phospholipids in the cell membrane are constantly moving
At increased temperature, greater kinetic energy, more movement
Membrane becomes more fluid and loses structure - increasing permeability
Carrier and channel proteins can denature, affect movement of substances

Question 2

Effect of organic solvents on membrane

Answer 2

Dissolve membranes, killing cells

Question 3

Why are alcohols used in antiseptic wipes?

Answer 3

They dissolve the membrane of bacteria, kill them and reduce risk of infection

Question 4

Why are non polar alcohol molecules dangerous?

Answer 4

They can enter the cell membrane and disrupt it, so it becomes more fluid and permeable

Question 5

Investigating membrane permeability

Answer 5

When beetroot cell membranes are disrupted, the red pigment is released and surrounding solution is coloured
Small pieces of beetroot are placed in test tubes and put in water baths where temperature is increased by 10oC intervals
Samples of the beetroot water were taken and colorimeter used to measure absorbance