What is the structure of haemoglobin?
Globular protein with a quaternary structure
(4 polypeptide chains)
4 chains= 2 alpha chains, 2 beta chains
What part of the haemoglobin binds to an oxygen molecule?
The prosthetic group- contains a iron ion
What is created when oxygen binds to haemoglobin?
Oxyhaemoglobin (HbO8)
Why is oxygen binding and unbinding a reversible reaction?
Oxygen is LOADED in the lungs and UNLOADED in the tissues
What is the process by which haemoglobin bind and unbinding with oxygen is called?
Loading or associating
Unloading or dissociating
What is cooperative binding?
When a molecule of oxygen binds to haemoglobin, it changes the tertiary structure slightly revealing other binding sites
Haemoglobins with a high affinity for oxygen…
take up oxygen more easily, but release it less easily
Haemoglobins with a low affinity for oxygen…
take up oxygen less easily, but release it more easily
What is the affinity for oxygen affected by?
The partial pressure of oxygen in the tissues surrounding the haemoglobin
What is the role of haemoglobin?
Transport oxygen
To be efficient at transporting oxygen, haemoglobin must…
- readily associate with oxygen at the surface where gas exchange takes place
- readily dissociate from oxygen at tissues requiring it
How does DNA lead to different haemoglobin molecules having different affinities for oxygen?
Different base sequence
Different amino acid sequence
Different tertiary and quaternary structure and shape
Different affinities for oxygen
Why might a person breathing in car-exhaust fumes lose consciousness?
(When carbon monoxide binds permanently to haemoglobin in preference to oxygen)
Carbon monoxide will occupy all site of haemoglobin instead of oxygen
No oxygen will be carried to tissues (brain)
Cease to respire and to function
Person loses consciousness
What shape is an oxygen dissociation graph?
S (sigmoid shape)
In the lungs where the partial pressure of oxygen is high…
Haemoglobin has a high affinity
Loads or associates with lots of oxygen
In the tissues with a low respiration rate, the partial pressure of oxygen…
Is relatively low
The affinity for oxygen decreases
In tissues with a high respiration rate, the partial pressure of oxygen is…
Much lower
How does the partial pressure of carbon dioxide affect oxygen-haemoglobin binding?
As partial pressure of CO2 increases, conditions are more acidic- haemoglobin changes shape.
The affinity of haemoglobin for oxygen decreases
Oxygen is released from haemoglobin
THE BOHR EFFECT
How does partial pressure of oxygen affect oxygen-haemoglobin binding?
As partial pressure of oxygen increases, the affinity of haemoglobin for oxygen increases
Oxygen binds tightly to haemoglobin
When partial pressure is low, oxygen is released from haemoglobin
What acid is produced when CO2 dissolves into blood plasma and reacts with water?
Carbonic acid
Why does the oxygen dissociation curve steeply increase?
The 2nd and 3rd oxygen molecules bind easily to the haemoglobin.
How is the affinity for oxygen affected when the oxygen dissociation curve is further to the left?
Greater affinity of haemoglobin for oxygen
Loads oxygen readily but unloads less easily
What is the Bohr effect?
The greater the concentration of carbon dioxide, the more readily the haemoglobin releases it oxygen
When a tissue is more active, more oxygen is unloaded. Why?
Higher rate of respiration More carbon dioxide is produced by tissues Lower pH Greater haemoglobin shape change More readily oxygen is unloaded More oxygen is available for respiration
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Section 1- Biological molecules84
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Section 1- Nucleic acids42
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Section 2- Cell structure81
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Section 2 - Transport across cell membranes100
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Section 2 - Cell recognition and the immune system58
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Section 3-Exchange59
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Section 3- Digestion29
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Section 3- Haemoglobin34
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Section 3- Circulatory system58
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Section 3- Mass Transport Plants27
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Section 4 - DNA, genes and protein synthesis47
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Section 4 - Genetic diversity30
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Section 4 - Biodiversity64
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Section 5- Photosynthesis53
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Section 5- Respiration52
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Section 5- Energy and ecosystems64
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Section 6- Response to stimuli57
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Section 6- Nervous co-ordination and muscles56
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Section 6- Homeostasis53
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Section 7 - Inherited change42
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Section 7 - Populations and evolution36
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Section 7 - Populations in ecosystems70
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Section 8- Gene expression59
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Section 8 - Recombinant DNA technology38
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Section 8 - In-vivo and In-vitro cloning etc. (until end)50
