Heamaglobin Flashcards
What is haemoglobin , heam groups and the co-operative nature of oxygen binding
Found in the red blood cells
Protein with a quaternary structure (more than 1 polypeptide chain)
Each of the four chains has a ham group (Fe) that can bind to an oxygen molecule making oxyhemoglobin
The cooperative nature of oxygen binding: First molecule of oxygen to bind causes a change in the shape of haemoglobin, this uncovers other binding sites making the binding of further oxygens easier.
Describe heamoglobin in loading and unloading
-loads oxygen at high partial presssure
-higher affinity of oxygen at high pp
-binding of one oxygen makes it easier for another oxygen to bind
-it’s transported as oyheamoaglobin in red blood cells
-unloads in respiring tissues
- as there is a lower partial pressure and affinity and high pp of co2
Why are some haemoglobin molecules different
-varies between animals
-causing it to have different affinities for oxygen
-different shapes due to genes , coding for different amino acid sequences and results in different primary - tertiary structures
What are the key points for a curve to be shifted to the left
-HAEMAGLOBIN has a higher affinity for oxygen
-loads oxygen more readily at lower partial pressure ensuring oxygen is supplied to respiring cells even when there’s not much available
-unloads oxygen at very very low partial pressure
How does carbon dioxide affect affinity
Respiring tissues produces carbon dioxide which dissolves and forms Carbonic acid and H*. The increases this reduces the ph. This causes a change in the haemoglobin’s shape and thus reduces the affinity of the haemoglobin for oxygen.
This is called the Bohr effect
• Carbon Dioxide causes the curve to shift to
the right
• The haemoglobins affinity for oxygen reduces
• Oxygen dissociates from the haemoglobin more readily
• More oxygen is unloaded to tissues for aerobic respiration.
explain how the graph shape shows co-operative binding
the graph is a s shape (sigmoid) shape
this means that at a low partial pressure there’s a slow increase in oxygen saturation
however , it starts to increase more as oxygen is easier to bind
