8.3 Haemoglobin Flashcards
(20 cards)
composition
2 alpha polypeptide chains
2 beta polypeptide chains
each chain has a prosthetic haem group attached to it
arrangement of polypeptide chains
hydrophobic R groups facing inwards; hydrophilic R groups facing outwards
why can Hb bind with O2?
presence of Fe2+ in Haem group
reaction between Hb & O2
Hb + 4O2 –> HbO8
reversible reaction
benefit of being soluble
can dissolve in blood plasma; transported easily
benefit of having small surface area: volume ratio
can be transported in large concentrations through narrow vessels
cooperative binding: meaning
every time a polypeptide chain binds with O2 the molecule undergoes a conformational change that makes subsequent binding easier
cooperative binding: impact
Hb has a high affinity for binding with O2
why does Hb unload O2 in the muscles? (3)
- low pO2; oxygen diffuses into tissue cells
- protons compete with O2 for Hb
- CO2 competes with O2 for Hb
reaction for formation of carbonic acid
CO2 + H2O –> H2CO3
disassociation of carbonic acid
H2CO3 –> H+ + HCO3-
reversible reaction
reaction for protons binding with haemoglobin
HbO2 + H+ –> H+Hb + O2
reversible reaction
reaction for CO2 binding w Hb
CO2 + HbO2 –> Hb-COO- + O2 + H+
what happens to hydrogencarbonate after carbonic acid disassociates?
it moves out of the RBC and into the blood plasma
name of molecule formed after Hb and CO2 bind
carbaminohaemoglobin
reasons for O2 uploading (2)
- low pCO2
2. O2 competes with CO2 & H+ for Hb
what happens to protons when RBCs are in the alveoli (ie. high pO2)?
combine with HCO3- to form carbonic acid, which turns back to water & CO2
CO2 TRANSPORTATION
list the different ways it is transported in the blood
as hydrogencarbonate ions (85%)
as carbaminohaemoglobin (10%)
dissolved in blood plasma (5%)
what is the bohr shift?
change in Hb saturation levels that occurs when CO2 conc. increases (curve shifts to right)
what is the chloride shift and why does it happen?
Cl- ions shift into RBCs as HCO3- ions move out. this is to balance the charge in the RBCs caused by protons and prevent it from getting too positive.
