Haemoglobin

Question 1

Haemoglobin

Answer 1

contained in Red blood cells (RBC)
large protein with quarternary structure
four polypeptide chains, each with a haem group (fe2+ ion) = RED COLOUR
high affinity for O2 => each HB molecule can carry four O2 molecules
in lungs, o2 joins to Hb to form oxyhaemoglobin
O2 dissociates from OHb near body cells, turning it back to Hb

Question 2

Partial pressure of O2

Answer 2

measure of O2 concentration

greater concentration of dissolved o2 in cells=higher partial pressure

Question 3

Haemoglobin Saturation

Answer 3

Hb affinity for O2 varies depending on partial pressure
O2 loads onto Hb where there’s HIGH pO2 (i.e. in alveoli)
O2 unloaded from OHb where there’s low pO2 (i.e. in respiring tissues)

Question 4

Dissociation curves

Answer 4

100% saturation means every Hb is carrying maximum 4 molecules of O2
0% saturation means no Hb are carrying any O2
top end of curve = high pO2 with high saturation = higher affinity of Hb (readily combines with O2)
bottom end of curve =low pO2 with low saturation = low affinity for O2 (readily releases O2)

Question 5

The Bohr Shift

Answer 5

caused by CO2 concentration or difference in pH (presence of lactic acid as a product of anaerobic respiration)
Hb has lower affinity with O2 at higher pCO2/pH
during respiration CO2/lactic acid produced
increases O2 unloading rate (OxyHb dissociation rate into O2 and Hb) so sigmeudal curve SHIFTS RIGHT
saturation is lower for given pO2 TF more O2 released

Question 6

Different Organisms

Answer 6

Organisms in environments w/ low conc. O2 have higher affinity for O2 TF dissociation curve LEFT of humans
More active organisms have high O2 demand = Hb with lower affinity for O2 = dissociation curve to the RIGHT of humans