Oxygen Transport Flashcards
What is myoglobin
Oxygen transport molecule for muscles
What Ion is at the centre of a Haemoglobin ring
Iron
How many nitrogen atoms are bound to the centre iron in the haem ring
4
How many oxygen molecules can bind to the iron in the centre of a haem group
1
What is proximal bound to the iron in haem
Histidine residue
What happens when oxygen binds to the Fe in haemoglobin
The age moves up into the plane of the ring, moving histidine up with it
How many polypeptides is myoglobin made up of
1
Which molecule has a high affinity for oxygen; haemoglobin or myoglobin
Myoglobin
What type of saturation curve does myoglobin produce
Hyperbolic
What type of saturation curve does haemoglobin produce
Sigmoidal
How many polypeptide chains is haemoglobin made up of
4 (2 alpha, 2 beta)
What are the 2 states of haemoglobin
R and T states
What is the T state of haemoglobin
Haem groups are not exposed, making it difficult for oxygen to bind. This is due to interactions between histidine and aspartate which stabilises the structure
What is the R state of haemoglobin
Haem groups are more exposed so oxygen can bind easier.
What sate does deoxyhaemoglobin exist in
T state
Which state of haemoglobin has the lower affinity for oxygen
T state
What affect does oxygen binding have on the state of haemoglobin
Gives a conformational change as histidine and Fe move up. This makes it easier for the next oxygen molecule to bind.
Why is the haemoglobin binding curve sigmoidal
As the haemoglobin transitions from the T to R state, its easier for oxygen to bind and so the curve becomes steeper
What does it mean by cooperative binding
The binding of one molecule of oxygen makes it easier for other oxygen molecules to bind
What molecule regulates oxygen binding
2,3-Bisphosphoglycerate
How does 2,3-BPG regulate oxygen binding
Decreases haemoglobin affinity for oxygen
What is the advantages in 2,3-BPG
It allows oxygen to be released in low partial pressure like the respiring tissues
What is the Bohr effect
When Hydrogen ions and carbon dioxide bind to haemoglobin lowering its affinity for oxygen
What does carbon monoxide do to haemoglobin
Binds very tightly preventing oxygen binding
What polypeptide chains are present in fetal haemoglobin
2 alpha and 2 gamma
What is the difference between fetal and maternal haemoglobin
Fetal has a higher affinity for oxygen allowing transfer from maternal to fetal
What is a thalassaemia
An imbalance between the number of alpha and beta chains
What is a beta thalassaemia
Decreased or absent beta chains
What results from beta thalassaemia
Alpha chain precipitate, fetal haemoglobin or haemoglobin made up of 4 gamma chains
