Haemoglobin
- Created by: jessicawarren
- Created on: 01-05-16 13:12
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- Haemoglobin
- Job
- 1) Red blood cells contain haemoglobin
- 2) Large protein w/ quarternary structure- made up of four polypeptide chains
- 3) Each chain has haem group- contains iron ion, gives haemoglobin red colour
- 4) Has high affinity for oxygen- each molecule can carry four O2 molecules
- 5) In lungs, O2 joins haemoglobin to form oxyhaemoglobin
- 6) Reversible reaction- when O2 dissociates from oxyhaemoglobin at body cell, turns back into haemoglobin
- Partial Pressure
- 1) Partial pressure of O2 is O2 concentration. Greater conc of O2= higher partial pressure
- 2) Same for CO2
- 3) Haemoglobin has a high affinity for oxygen when the partial pressure is high (loads) and vice versa (unloads)
- 4) O2 enters blood capillaries at alveoli in lungs. Alveoli have high partial pressure, so O2 loads onto haemoglobin
- 5) When cells respire, they use up oxygen. Lowers partial pressure- oxygen unloaded at respiring cells
- 6) Haemoglobin returns to lungs to pick up more O2
- Dissociation Curve
- Where pO2 is high (lungs) haemoglobin has high affinity for O2- will readily combine. High saturation
- Where pO2 low (respiring tissue) haemoglobin has low affinity for O2, unloads oxygen. Low saturation
- S shaped: Haemoglobin binds with first O2 molecule, shape alters to make it easier for other molecules to join.
- As Hb gets saturated, becomes harder for more molecules to join. Steep in middle of curve (easy to join) , shallow at each end (hard to join)
- CO2 Concentration
- Haemoglobin gives up O2 more readily at higher pressures of CO2
- 1) Respiring cells produce CO2, raises pCO2
- 2) Increases rate of O2 unloading- dissociation curve shifts to the right- saturation of blood w/O2 lower for given partial pressure, more oxygen being released
- 3) Bohr effect
- Different haemoglobin
- Different organisms have different types of haemoglobin with different oxygen transporting capacities
- 1) Organisms in environment with low conc of O2 have haemoglobin with higher affinity for O2 than humans- curve falls to left
- 2) Very active organisms with high O2 demand have haemoglobin with a lower affinity for O2 than humans- curve to right of human one
- Job
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