proteins

Question 1

adult haemoglobin

Answer 1

contains two alpha and two beta subunits

Question 2

foetal haemoglobin

Answer 2

contains two alpha and two gamma subunits

Question 3

cooperative binding of oxygen in haemoglobin

Answer 3

haemoglobin must bind oxygen effeciently in the lungs, and release oxygen in the tissues. so, binding of one oxygen makes the affinity at other sites higher, release of an oxygen reduces the affinity at other sites. a sigmoidal curve is the signature of cooperativity.

Question 4

glycosylation as a PTM

Answer 4

• attachmemt of a carb
• protects against digestion
• found particularly in extracellular and cell surface proteins
• sugars attached to asparagine (N), serine (S) and threonine (T) residues
• involved in cell-to-cell recognition
• aids in protein folding and can influence targeting of newly synthesised protein to its destination

Question 5

ABO blood groups

Answer 5

• O-linked olgiosaccharides on RBC proteins and lipids.
• all antigens share the O carbohydrate foundation
• A and B have an extra monosaccharide:
  A= N-acetylgalactosamene
  B= galactose

Question 6

hydroxylation of proline and lysine

Answer 6

collagen- polypeptide consists of several hundred repeats of Gly-Pro-Hydroxypro.
hydrolysed lysine residues are involved in collagen cross-linking
Vit C required for pro and lys hydroxylation- deficiency leads to scurvy

Question 7

sickle-cell anaemia

Answer 7

• caused by a single change in the beta subunit of haemoglobin
• individuals with a single change are generally asymptomatic.
  with 2 copies the haemoglobin aggregate, distorting erythrocytes. sickle cells obstruct capillaries causing intense pain and organ damage.