Structure of haemoglobin Flashcards
What is haemoglobin? What group does it belong to?
- Haemoglobin is a quarternary structure protein.
- Belongs to “haemoglobins” group.
What are “haemoglobins?”
- Haemoglobins are a group of chemically similar molecules found in many different organisms.
What is the role of haemoglobin/ red blood cells?
- Role: to transport oxygen.
What is meant by the phrase “affinity of haemoglobin for oxygen?”
- Ability of haemoglobin to bind oxygen.
What is meant by the phrase “saturation of haemoglobin with oxygen?”
- When haemoglobin is holding the maximum amount of oxygen it can bind.
What is meant by the phrases “loading” and “unloading” of haemoglobin?
- Loading: binding of haemoglobin to oxygen.
- Unloading: unbinding of oxygen from haemoglobin.
What is on the x and y axis of the oxyhaemoglobin dissociation curve?
- x: oxygen partial pressure (ie. conc of oxygen.)
- y: saturation of haemoglobin (%)
Name of curve with partial pressure on x axis ans saturation of haemoglobin on y axis.
- Oxyhaemoglobin dissociation curve
Describe the loading, transport and unloading of oxygen in relation to the oxyhaemoglobin dissociation curve.
- Oxygen is loaded in regions with a high partial pressure of oxygen (ie. alveoli.) ie. HIGHER AFFINITY to oxygen.
- Oxygen is unloaded in regions of low partial pressure of oxygen (e.g., respiring tissues.) ie. LOWER AFFINITY to oxygen.
Why is it useful for haemoglobin to have a lower affinity to oxygen in areas of low partial pressure?
- Means that oxygen will unload from the haemoglobin.
- Respiring cells tend to have low partial pressure of O2 - using O2 up.
- O2 unbinding from haemoglobin will mean O2 will be supplied to respiring cells.
Why is it useful for haemoglobin to have a higher affinity to oxygen in areas of high partial pressure?
- Means haemoglobin will bind to oxygen, haemoglobin will become saturated with oxygen - oxygen can be transported to respiring cells.
Oxyhaemoglobin dissociation curve. Why does the saturation of haemoglobin increase as the partial pressure increases in terms of co-operative binding of oxygen?
- First oxygens binding to haemoglobin causes the change in shape of haemoglobin.
- Change in shape of haemoglobin makes the binding of further oxygens easier.
What is it called when first oxygen binds to haemoglobin, causing the haemoglobin to change shape so that further oxygens bind more easily?
- The co-operative nature of oxygen binding to haemoglobin.
What is “The Bohr Effect?”
- The Bohr Effect is when a high carbon dioxide concentration causes the oxyhaemoglobin curve to shift to the right.
- The affinity for oxygen decreases becauses the acidic carbon dioxide changes the shape of haemoglobin slightly.
On an oxyhaemoglobin dissociation curve illustrating The Bohr Effect, what will be the saturation of oxygen at a lower pH vs higher pH (from carbon dioxide) at the same partial pressure of oxygen?
- Higher pH (low partial pressure of carbon dioxide in the alveoli) : higher saturation of oxygen, curve shifts to the left - increased affinity, therefore uploads more oxygen.
- Lower pH (high partial pressure of carbon dioxide at respiring tissues) : lower saturation of oxygen, curve shifts to the right, decreased affinity therefore unloads more oxygen.
True or False
All animals have the same type of haemoglobin. If false, why?
- False.
- Animals have different types of haemoglobin with different oxygen transport properties/ different affinities for oxygen, helping them to be adapted to their environment.
What is the haemoglobin of:
- a foetus
like and why? How would the oxyhaemoglobin dissociation curves shift relative to human curve?
- Feotus: oxyhaemoglobin dissoication curve will shift to the left. Haemoglobin will have higher affinity for oxygen at same partial pressure of O2, feotus cannot inhale and exhale, only source of oxygen from mother’s red blood cells.
What is the haemoglobin of:
- a llama
like and why? How would the oxyhaemoglobin dissociation curves shift relative to human curve?
- Llama: oxyhaemoglobin dissociation curve will shift to the left. Haemoglobin will have higher affinity for O2 at same partial pressure of O2.
- Llamas live at high altidues, where there is a lower partial pressure of O2.
What is the haemoglobin of:
- a dove
like and why? How would the oxyhaemoglobin dissociation curves shift relative to human curve?
- Dove: Oxyhaemoglobin dissociation curve will shift to the right. Hameoglobin will have lower affinity for O2 at same partial pressure of O2. Oxygen will unload from haemoglobin more readily.
- Doves have faster metabolism than humans so need more oxygen for respiration, to provide energy for muscle contraction.
What is the haemoglobin of:
- a worm
like and why? How would the oxyhaemoglobin dissociation curves shift relative to human curve?
- Worm: oxyhaemoglobin dissoication curve will shift to the left. Haemoglobin will have higher affinity for oxygen at same partial pressure of O2.
- They live underground where there is a lower partial pressure of oxygen.
past paper Q.
Give formula for calculating percentage saturation of haemoglobin with oxygen.
oxygenated haemoglobin/ maximum saturation x 100.
Past paper Q
The first molecule of oxygen to bind causes a change in the shape of the haemoglobin molecule.
This change of shape makes it easier for other oxygen molecules to bind to the haemoglobin molecule.
Explain how the graph provides evidence for this.
- At low partial pressure: little increase in saturation as O2 increases.
- Rapid rise as it gets easier for O2 to bind.
Past Paper Q
Advantage of haemoglobin having lower affinity
- Easier unloading of O2.
