7.1 + 7.2 Haemoglobin

Question 1

Primary structure of haemoglobin

Answer 1

sequence of amino acids in the four polypeptide chains

Question 2

Secondary structure of haemoglobin

Answer 2

Each of the polypeptide chains is coiled into a helix

Question 3

Tertiary structure of haemoglobin

Answer 3

Each polypeptide chain is folded into a precise shape

Question 4

Quaternary structure of haemoglobin

Answer 4

All four polypeptides are linked together to form spherical molecule

Each polypeptide is associated with haem group(contains Fe2+ ion)

Each ferrous iron ion can combine with single oxygen- so four O2 molecules can be carried by single haemoglobin molecule

Question 5

Loading/associating

Answer 5

Process where haemoglobin binds with oxygen
Occurs in the lungs

Question 6

Unloading/dissociating

Answer 6

Process where haemoglobin releases its oxygen
Occurs in the tissues

Question 7

Oxygen affinity

Answer 7

Haemoglobin with higher affinity take up oxygen more easily, but release it less easily

Haemoglobin with low affinity take up oxygen less easily, but release it more easily

Question 8

Changing haemoglobin affinity

Answer 8

The shape of the haemoglobin changes in the presence of substances e.g. carbon dioxide
- binds more loosely to oxygen so releases it

Question 9

Oxygen dissociation curve

Answer 9

relationship between saturation of haemoglobin with oxygen and partial pressure of oxygen

Question 10

High oxygen affinity

Answer 10

In gas exchange surface
- low CO2 concentration
- associates oxygen
- shifts oxygen dissociation curve to left

Question 11

Low oxygen affinity

Answer 11

in respiring tissues
- high co2 concentration
- dissociates oxygen (bohr effect) into muscles
- shifts oxygen dissociation curve to right

Question 12

Low oxygen concentration

Answer 12

little oxygen binds to haemoglobin
- polypeptide are closely united so oxygen finds it difficult to bind to site

Question 13

High oxygen concentration

Answer 13

With majority of binding sites occupied(3/4), it is less likely that oxygen molecule will find an empty site to bind to
- gradient of curve reduces and plateaus

Question 13

Increase in oxygen concentration

Answer 13

Binding of first oxygen molecule induces other subunits to bind to oxygen
- changes quaternary shape of haemoglobin
- positive cooperarativity
- gradient of curve steepens

Question 14

ODC shifted to left

Answer 14

The greater the affinity for oxygen
- loads oxygen more readily
- unloads it less easily

Question 15

ODC shifted to right

Answer 15

The lower the affinity for oxygen
- unloads more readily into tissue
- loads less easily

Question 16

Gas exchange

Answer 16

• CO2 constantly being removed
• pH is raised due to low CO2 conc
• higher pH changes shape of haemoglobin so it loads O2 easily
• higher affinity

Question 17

Tissues

Answer 17

• Co2 is beind produced by respiration
• lowers pH(acidic)
• pH changes haemoglobin so it unloads o2 more easily
• lower affinity for o2

Question 18

different haemoglobin

Answer 18

• each species has different amino acid base sequence for haemoglobin
• different oxygen dissociation curves
• different affinities