12. Haemoglobin Flashcards
(9 cards)
What is the structure of haemoglobin?
Protein with a quaternary structure. It has 4 polypeptide chains of 4 subunits each with a haem group in the centre (each haem group(with iron atom) binds to 1 molecule of O2) Subunits are: alpha chains, beta chains.
Oxyhemoglobin formed when oxygen binds in high ppO2.
Haemoglobin transports O2 in rbc
How is the red blood cell adapted for haemoglobin?
No nucleus- more space for haemoglobin
Biconcave shape - Large sa:vol ratio enable O2 to diffuse quickly.
What does the oxygen dissociation curve show about ppO2? What is the shape of the graph?
In the lungs at higher ppO2, haemoglobin has a higher affinity for O2 so loads more readily giving a higher saturation.
In respiring tissues at lower ppO2, haemoglobin has a lower affinity for O2 so unloads more readily to be used by respiring tissues in aerobic respiration.
Has a sigmoidal shape.
What is cooperative bonding?
When one O2 binds to haemoglobin, it changes the tertiary structure uncovering another binding site (containing an iron ion) making it easier for other molecules of O2 to bind. Each haemoglobin can have 4 O2 molecules.
This ensures rapid loading of O2 in lungs and rapid unloading in tissues
What is the effect of organisms in low O2 environment on the OCD graph ?
low O2 environment, OCD shifts left. At lower ppO2 have a higher affinity for O2 than humans so O2 unloads/loads more readily for aerobic respiration in respiring tissue and the lungs.
What is the effect of increasing CO2 concentration on the dissociation of oxyhemoglobin? How does CO2 lower pH? And what is the name of the effect?
High ppCO2 causes the OCD graph to shift right so at lower ppO2 haemoglobin has a lower affinity for O2 so unloads more readily into respiring tissues for aerobic respiration producing CO2.
Co2 dissolves in blood forming acid which lowers pH as it increases H+ concentration. The lower pH could change the shape of the tertiary structure of the Hb lowering the affinity.
The Bohr Effect
What happens to the OCD if a species is more active?
Shifts right so at lower ppO2 haemoglobin ppO2 haemoglobin has a lower affinity for O2 so unloads more readily into respiring tissues to use in aerobic respiration.
Why does foetal Hb have a higher affinity for O2 than adult Hb?
Foetal Hb has higher affinity for O2 at lower ppO2 than adult Hb so O2 unloads more readily from adult Hb and diffuses across the placenta and loads on to foetal Hb (which can be used for aerobic respiration.)
What affect on the OCD graph do small organisms have (e.g. mice)?
Small organisms shift OCD right. At low ppO2 haemoglobin has a lower affinity for O2 so unloads more readily into respiring so more aerobic respiration can take place producing heat energy to regulate body temp.
Due to having a large SA:Vol ratio they lose heat quickly.
