Haemoglobin 3B

Question 1

Haemoglobin Structure

Answer 1

Large protein with 4 polypeptide chains, quaternary structure, each chain contains a haem group which contains an iron ion and makes haemoglobin red. Each molecule can carry 4 oxygen atoms

Question 2

What type of affinity for oxygen does a haemoglobin molecule have

Answer 2

A high affinity

Question 3

What is the molecule called when haemoglobin joins with oxygen

Answer 3

oxyhaemoglobin

Question 4

Oxyhaemoglobin equation

Answer 4

Hb+4O2 -> <- HbO8

Question 5

Define partial pressure

Answer 5

The measure of a concentration of a substance in another substance

Question 6

What does affinity for oxygen depend on

Answer 6

Partial pressure

Question 7

When does oxygen bind to haemoglobin

Answer 7

when there is a high PO2

Question 8

When does oxygen unload from haemoglobin

Answer 8

when there is a low PO2

Question 9

Explain the oxygen dissociation curve

Answer 9

Where PO2 is high (eg in lungs) haemoglobin has a high affinity for oxygen so it has a high oxygen saturation

Where PO2 is low (eg in respiring tissues) haemoglobin has a low affinity for oxygen which means oxygen dissociates so it has a low oxygen saturation

Question 10

Explain the Bohr shift

Answer 10

When cells respire they produce more CO2 raising the PCO2. This increases the rate of oxygen unloading as oxygen dissociates. The saturation of blood with oxygen is lower for a given partial pressure meaning that more oxygen is released

Question 11

How does haemoglobin work in different organisms

Answer 11

Organisms which live in areas where oxygen concentration is low has haemoglobin with a higher affinity for oxygen than humans.

For active organisms that have a high demand for oxygen, have haemoglobin with a lower affinity for oxygen