haemoglobin

Question 1

describe the role of red blood cells and haemoglobin in oxygen transport.

Answer 1

red blood cells contain lots of Hb, they have no nucleus and is a biconcave shape - so theres more space for Hb, high surface area to volume ratio & short diffusion distance.
Hb binds with oxygen at gas exchange surfaces (lungs) where pressure of oxygen is high to form oxyhaemoglobin which transports oxygen.
each can carry four oxygen molecules, one at each haem group.
Hb disassociates from oxygen near tissues where pressure is low.

Question 2

describe the structure of haemoglobin.

Answer 2

• has a quaternary structure.
• made of 4 polypeptide chains.
• each chain contains a haem group containing an iron ion (where oxygen binds)
• globular structure.

Question 3

describe the loading, transport and unloading of oxygen in respiring cells.

Answer 3

(areas with low pressure)
- haemoglobin is oxygenated.
- first o2 molecule disassociates with haemoglobin, causes conformational change, reducing affinity.
- next o2 molecule can unbind more easily, changing shape and so on until all molecules are released.

Question 4

describe the loading, transport and unloading of oxygen in gas exchange surfaces (lungs/alveoli)

Answer 4

(areas with high pressure)
- haemoglobin is deoxygenated.
- first o2 molecule binds, causing conformational change to Hb.
- this makes haemoglobin have a higher affinity for o2 - so the next molecule binds, changing shape again and increasing affinity until all 4 molecules are bound.

Question 5

explain why different types of haemoglobin can have different oxygen transport properties.

Answer 5

• different types of Hb are made of polypeptide chains with slightly different amino acid sequences
• resulting in different tertiary/ quaternary structures
• so they have different affinities for oxygen.