ICPP 1 Membrane Bilayer - Proteins

Question 1

What are key structural features which enable protein function?

Answer 1

Flexible
Elastic

Question 2

Modes of motion in proteins

Answer 2

Lateral diffusion
Rotation
Conformational change

Question 3

What mode of motion is not permitted in proteins?

Answer 3

Flip flop

Question 4

What mode of motion is allowed in proteins but not lipids?

Answer 4

Conformational change

Question 5

Classification of proteins

Answer 5

Integral proteins
Peripheral proteins - extracellular + intracellular

Question 6

What protein can be removed by changes in pH and why?

Answer 6

Peripheral proteins
Attraction is lost

Question 7

Function of intracellular peripheral proteins

Answer 7

Enzymes
Regulates channels + transporters
Enhances flexibility + elasticity of whole membrane
Protects cell integrity from mechanical disruption

Question 8

Location of intracellular peripheral proteins

Answer 8

Internal membrane face

Question 9

How do intracellular peripheral proteins enhance flexibility + elasticity of the whole membrane?

Answer 9

By their role in organisation of cortical cytoskeleton

Question 10

How to intracellular peripheral proteins protect cell integrity from mechanical disruption?

Answer 10

Disperses forces

Question 11

Location of extracellular peripheral proteins

Answer 11

External membrane face

Question 12

Function of extracellular peripheral proteins

Answer 12

Enzymes
Antigens - recognise as self
Adhesive molecules with extracellular matrix

Question 13

Location of integral proteins

Answer 13

Span all or some of the membrane

Question 14

Bonding with integral proteins

Answer 14

• Non-polar bonding within hydrophobic interior of lipid bilayer
• Polar interactions between hydrophilic head + polar protein residuals

Question 15

Function of integral proteins

Answer 15

Channels
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