paper 1: Mass Transport in Animals Flashcards
describe the structure of haemoglobin
- each haemoglobin is made up of 4 polypeptide chains
- therefore has a quaternary structure because it is made up of more than one polypeptide chain
- each polypeptide has a haem group containing Fe2+ which binds one oxygen molecule
- so each haemoglobin molecule can bind 4 oxygen molecules
write an equation to show how haemoglobin and oxygen combine
oxygen + haemoglobin <—> oxyhaemoglobin
define partial pressure of oxygen
the measure of the concentration ofoxygen present in tissues
define loading/ association
when oxygen is taken up by haemoglobin
define unloading/ dissociation
when oxygen is released form haemoglobin
define affinity
how well the oxygen is bound to the haemoglobin
define percentage saturation
the amount of oxygen that is combined with haemoglobin
write the formula for working out oercentage saturation of haemoglobin
oxygenated haemoglobin
_____________________________ X 100
maximum saturation
describe the loading of oxygen at the lungs
- high partial pressure of oxygen
- haemoglobin has a high affinity for oxygen
- haemogobin becomes saturated with oxygen
describe the unloading of oxygen from oxyhaemoglobin at respiring tissues
- low partial pressure of oxygen
- haemoglobin has a low affinity for oxygen
- haemoglobin becomes unsaturated with oxygen
describe why the oxygen dissociation curve has a sigmoid shape
- the binding of the first molecule of oxygen to haemoglobin changes the tertiary structure and shape of haemoglobin
- this uncovers another haem group for oxygen to bind to
- so the next oxygen molecule binds more readily to haemoglobin
describe the Bohr Effect
- in the presence of carbon dioxide the oxygen dissociation curve shifts to the right
- because the affinity of haemoglobin for oxygen is reduced
- so partial pressure of O2 found in tissues, the haemoglobin is less saturated
- oxygen unloads more readily to be used for aerobic respiration at the tissues
- the delays the onset of anaerobic respiration at the tissues so less lactic acid is produced
why does Bohr Shift occur
- carbon dioxide decreases the pH of blood which alters the tertiary strucure of haemoglobin
describe and explain the effect of increasing carbon dioxide concentration on the oxyhaemoglobin dissociation curve
- curve shifts to the right
- affinity of haemoglobin for oxygen is reduced so oxygen unloads more readily
- because carbon dioxide decreases pH of the blood which chnages the tertiary structure of haemoglobin
describe what kind of organism shows curve A
- type of haemoglobin found in adult humans and many other organisms that live on land at sea level
describe and explain what kind of organisms have haeomoglobin at curve B
- found in species thst live in environments where environmentalpartial pressure is low (high altitude/ bottom of lakes)
- this is because there is not a lot of O2 available in the environment, normal haemoglobin would not fully saturated the gas excahnge surface
- instead they have a form of haemoglobin where the dissociation curve is shifted to the left
- the haemoglobin will fully saturate at the loer environmental pO2
- similar to human foetal haemoglobin curve