4.5

Question 1

structure of haemoglobin in relation to its role in transport of resp gases

Answer 1

haemoglobin = large globular protein - 4 ham grps - 4 peptide chains
- each harm grp can bind to one o2 molecule <-> oxyhemoglobin
- 1st o2 is difficult to bind to haem - but this then alters shape of molecule so easier for next o2 to bind - also means that also gets progressively harder for o2 to leave/dissociate harm grp

Question 2

why is o2 always diffusing in and binding to RBC

Answer 2

in lungs = high conc of O2, diffuses into RBC - loads + binds to haem grp - but free O2 conc in cytoplasm of RBC therefore always a conc gradient - so more o2 diffusing in

Question 3

what is the Bohr effect

Answer 3

changes in o2 dissociation curve that result as the CO2 level changes

Question 4

how does affinity for o2 change in dif co2 cones

Answer 4

• high co2 levels = lower affinity for o2 so easily more readily lost

Question 5

how is co2 transported in blood

Answer 5

• in respiring tissue - higher conc of CO2 - diffuses into RBC + combines w water
• Co2 + H20 <- (this is catalysed by carbonic anhydrase)-> H2Co3 (carbonic acid) <-> H+ + HCO3-

Question 6

Understand the similarities and differences between the structures and functions
of haemoglobin and myoglobin.

Answer 6

• myo = 1 harm grp - acts as O2 store as only releases o2 in v low conc - high CO2 conc
• higher affinity than haem

Question 7

Understand the significance of the oxygen affinity of fetal haemoglobin as
compared to adult haemoglobin.

Answer 7

• higher affinity
• so that feral blood can remove o2 from mum’s blood - also countercurrent exchange system to maximise o2 transfer