Red Cell Metabolism

Question 1

Describe Glycolysis

Answer 1

• main function is to generate 2 molecules of ATP
• ATP required for maintenance of red cell shape

Question 2

What is the role of 2,3 - BPG

Answer 2

• only binds doexygenated haemoglobin
• binds to lysine & histidine residues on two beta chains
• this reduces the affinity of oxygen for haemoglobin so released oxygen is given up to tissues

Question 3

Describe foetal haemoglobin

Answer 3

• reduced affinityfor 2,3-BPG
• this is why it has greater affinity for oxygen than adult HbA

Question 4

What are some functions of Haemoglobin?

Answer 4

• transport of oxygen
• each haemoglobin has 4 haem groups & 4 polypeptide chains
• the haem pocket is hydrophobic , as oxygen enters it forms a weak bond with Fe2+

Question 5

Describe Cooperativity

Answer 5

• upon binding with oxygen - there is a rearrangement of electrons
• iron moves into plane of haem ring, this pulls with it the F8 histidine
• there is then a conformational change at the a1b2 contact point
• this allows step wise oxygenation of other three haem groups

Question 6

What is the Bohr Effect ?

Answer 6

certain facotrs can shift the saturation curve - pH or 2,3-BPG
- Shift to the left = haemoglobin has a greater affinity for oxygen
- shift to the right = lower affinity for oxygen

Question 7

How does pH effect the equilibrium ?

Answer 7

• increases H+
• pushes equlibirum to the left
• pushes saturation curve to the right - reduces affinity of HbA for oxygen

Question 8

Describe Pentose Phosphate Shunt

Answer 8

1. generation of 5C sugars
2. mechanism to protect against oxidant damage to RBC

Question 9

What are the main 2 oxidants ?

Answer 9

1. superoxide
2. Hydrogen peroxide

Question 10

What can occur if oxidants are left unchecked?

Answer 10

• they can oxidise Hb, this leads to Heinz body formation