Haemoglobin

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  • Created by: LucySPG
  • Created on: 01-06-13 12:05
What is the primary structure of haemoglobin?
Consists of four polypeptide chains
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What is the secondary structure of haemoglobin?
Each polypeptide chain is coiled into a helix
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What is the tertiary structure of haemoglobin?
Each polypeptide chain is folded into a precise shape
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What is the quaternary structure of haemoglobin?
All four polypeptide chains are linked together to form a spherical molecule. Each polypeptide is associated with a haem group.
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What is the role of haemoglobin?
To transport oxygen
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Explain two ways in which haemoglobin is efficient at transporting oxygen
It readily associates with oxygen at the surface where gas exchange takes place and it readily dissociates from oxygen at those tissues requiring it
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What does affinity mean?
How well it is attracted to oxygen
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What is the affinity of haemoglobin for oxygen when oxygen concentration is high and carbon dioxide levels are low at the gas exchange surface?
High so oxygen is attached
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What is the affinity of haemoglobin for oxygen when oxygen concentration is low and carbon dioxide levels are high at respiring tissues?
Low so oxygen is released
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What does haemoglobin with a high affinity do?
Takes up oxygen readily but releases it less readily
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What does haemoglobin with a low affinity do?
Takes up oxygen less readily but releases it more readily
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An organism living in an environment with little oxygen requires haemoglobin that....
Readily combines with oxygen
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An organism with a high metabolic rate requires haemoglobin that....
Releases oxygen readily into the tissues
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Why does haemoglobin have different affinities for oxygen?
Different haemoglobin molecules have different sequences of amino acids and therefore slightly different shapes. Whether it has a high or low affinity depends on its shape.
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What is the name of the process by which haemoglobin combines with oxygen?
Loading or associating
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What is the name of the process by which haemoglobin releases its oxygen?
Unloading or dissociating
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What is happening to carbon dioxide at the gas exchange surface?
Carbon dioxide is constantly being removed
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What happens to the pH due to the low level of carbon dioxide?
It is raised
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What effect does the change in pH have on the shape of the haemoglobin molecule?
It changes it into one that enables it to load oxygen more readily
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What effect does the change in shape of the haemoglobin have on the affinity for oxygen?
Increases the affinity for oxygen so it is not released whilst being transported in the blood to the tissues
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What is being produced by respiring cells?
Carbon dioxide
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What effect does carbon dioxide have on the pH of the blood?
Lowers the pH
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What effect does the change in pH have on the shape of the haemoglobin?
Changes the shape into one with a lower affinity for oxygen
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What does the haemoglobin do?
Release oxygen into the respiring tissues
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What happens to haemoglobin when it is exposed to different partial pressures of oxygen?
It doe not absorb oxygen evenly
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What happens to the saturation of oxygen when the partial pressure of oxygen is high?
High saturation of oxygen
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What happens to the affinity of oxygen when the partial pressure of oxygen is high?
High affinity
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What happens to the saturation of oxygen when the partial pressure of oxygen is low?
Low saturation of oxygen
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What happens to the affinity of oxygen when the partial pressure of oxygen is low?
Low affinity for oxygen
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Why does the graph tail off at high oxygen concentrations?
The haemoglobin is almost saturated with oxygen
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Why is the graph S shaped?
Because when the haemoglobin combines with the first oxygen molecule, its shape alters in a way that makes it easier for other molecules to join too
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Why does the curve have a steep bit?
Because as the haemoglobin starts to become saturated, it gets harder for more oxygen molecules to join and as a result the curve has a steep bit
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What is the affinity when the curve is further to the left?
High affinity for oxygen
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What is the affinity when the curve is further to the right?
Low affinity for oxygen
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Other cards in this set

Card 2

Front

What is the secondary structure of haemoglobin?

Back

Each polypeptide chain is coiled into a helix

Card 3

Front

What is the tertiary structure of haemoglobin?

Back

Preview of the front of card 3

Card 4

Front

What is the quaternary structure of haemoglobin?

Back

Preview of the front of card 4

Card 5

Front

What is the role of haemoglobin?

Back

Preview of the front of card 5
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