collagen, estrogen receptor, myoglobin and haemoglobin

Question 1

what feature of collagen allows it to form a tightly packed alpha helix?

Answer 1

glycine in 3rd position

Question 2

what structural feature of collagen allows it to form cross links between chains?

Answer 2

lots of OH groups

Question 3

why does shortage of vitamin C lead to scurvy?

Answer 3

vit C co-factor for prolyl hydroxylase

hydroxyproline depleted

Question 4

how does the drug tamoxifen work?

Answer 4

binds to ER without activating it

Question 5

what is meant by the term ‘prosthetic group’?

Answer 5

a compound that is permanently associated with a protein and contributes to its function

Question 6

which form of iron is found in haem?

Answer 6

ferrous Fe3+

Question 7

what role does histidine play in the binding of oxygen to haem?

Answer 7

histidine promotes the breaking of electrostatic attractions at the sub unit interface allowing the relative rotation of the subunits, moves Fe2+ into centre of ring

Question 8

which factors promote the release of o2 into the tissues?

Answer 8

• H+ favours deoxy form
• co2 favours deoxy form
• BPG binds to tetramer

Question 9

what structural problem causes sickle cell anaemia?

Answer 9

mutation in beta chains

Question 10

why does foetal haemoglobin have an increased affinity for O2?

Answer 10

binds BPG more tightly

Question 11

why does BPG affect Hb but not Mb?

Answer 11

Mb is a single sub unit, BPG binds to the tetramer