CW4: Protein diversity

Question 1

What are the four major groups of protien?

Answer 1

• Structural
• Interactive
• Passive
• Multifunctional

Question 2

What are the two types of structural protein? Give examples of each.

Answer 2

• Static, e.g. keratin (hair), collagen (skin)
• Dynamic, e.g. actin, tubulin

Question 3

What are the five types of interactive proteins? Give examples of each.

Answer 3

• Enzymes, e.g. ribonuclease, β-galactosidase
• Pumps and channels, e.g. Na²⁺ pump
• Binding, e.g. haemoglobin, myoglobin
• Receptors, e.g. oestrogen receptors, vascular endothelial growth factor (VEGF) receptor
• Recognition, e.g. antibodies, DNA-binding proteins

Question 4

What are the two types of passive proteins? Give examples of each.

Answer 4

• Food stores, e.g. seed proteins
• Antifreeze proteins

Question 5

What is one type of multifunctional protein? Give an example.

Answer 5

Contractile, e.g. myosin

Question 6

Give three examples of inherited diseases and the mutations within the proteins.

Answer 6

1. Sickle cell anaemia – glutamate₆ to valine in haemoglobin β-chain
2. Gaucher disease – leucine₄₄₄ to proline in glucocerebrosidase
3. Cystic fibrosis – phenylalanine₅₀₈ deletion in CFTR

Question 7

How can mutations be made deliberately during research?

Answer 7

Serine can be mutated to alanine (a negative control, as alanine cannot be phosphorylated)

Serine can be mutated to glutamate to hold a negative charge (positive control) to act as though the serine has been permanently phosphorylated

Question 8

How does a potassium channel work? Why is it harder to study?

Answer 8

There is a selective filter on the outside of the cell, that prevents larger positive molecules from passing (K⁺ is small enough to pass through). This is called a restriction point and is caused by negatively charged amino acids at the sides of the channel.

It is hard to study because it must be studies within membranes and its preferred environment is water-free but we usually use aqueous environments