Mass transport Animals- haemoglobin

Question 1

What is haemoglobin (hb) and its structure ?

Answer 1

-Large protein with a quaternary structure (made up of more than one polypeptide chain)
-Each chain has haem group, which contains an iron ion, gives haemoglobin its red colour.
-Has a high affinity for oxygen- each molecule can carry four oxygen molecules
-In the lungs, oxygen joins to haemoglobin in red blood cells to form oxyhaemoglobin. (reversible reaction)

Question 2

What is the partial pressure of oxygen?

Answer 2

-A measure of oxygen concentration
-Greater the concentration of dissolved oxygen in cells, the higher the partial pressure is
-Haemoglobin’s affinity (tendency to combine with oxygen) for oxygen varies depending on the partial pressure of oxygen

Question 3

How the haemoglobin and oxyhaemoglobin work in the body?

Answer 3

-Oxygen loads onto haemoglobin to form oxyhaemoglobin where theres a high partial pressure of oxygen
-Where theres a low partial pressure of oxygen, oxyhaemoglobin unloads its oxygen
1)Oxygen enters blood capillaries at the alveoli in the lungs. Alveoli have a high partial pressure of oxygen so oxygen loads onto haemoglobin
2)When cells respire, they use oxygen- lowers the partial pressure of oxygen. Red blood cells deliver oxyhaemoglobin to respiring tissues, where it unloads its oxygen
3)Haemoglobin then returns to the lungs to pick up more oxygen

Question 4

What does a dissociation curve shows?

Answer 4

Shows how saturated the haemoglobin is with oxygen at any given partial pressure

Question 5

What does it mean when partial pressure of oxygen is high on a dissociation curve?

Answer 5

-Where partial pressure of oxygen is high (in lungs) haemoglobin has a high affinity for oxygen so it has a high saturation of oxygen

Question 6

What does it mean when partial pressure of oxygen is low on a dissociation curve?

Answer 6

-Where partial pressure of oxygen is low (in respiring tissues) haemoglobin has a low affinity for oxygen which means it releases oxygen rather than combines with it. Has a low saturation of oxygen

Question 7

What happens to haemoglobin when it combines with the first oxygen molecule vs when it starts to become saturated?

Answer 7

When it combines with the first oxygen molecule, its shape alters in a way that makes it easier for other molecules to join too.
When it becomes saturated, it gets harder for more oxygen molecules to join. As a result dissociation curve graph have a steep bit in the middle where its easy for oxygen molecules to join and shallow bits at each end where its harder

Question 8

What makes the dissociation curve to shift right?

Answer 8

-Partial pressure of CO2 shifts the dissociation curve to right

Question 9

Effect of CO2 on the oxygen unloading-

Answer 9

-When cells respire they produce CO2 which increases the partial pressure of CO2
-This increases the rate of oxygen unloading
-dissociation curve shifts right
-Saturation of blood with oxygen is lower for a given partial pressure of oxygen meaning that more oxygen is being released
-Called the Bohr effect

Question 10

What kind of haemoglobin does organisms have that live in environment with a low concentration of oxygen?

Answer 10

-Have a haemoglobin with a higher affinity for oxygen than human haemoglobin- dissociation curve is to left of ours

Question 11

What kind of haemoglobin does organisms have that are very active and have a high oxygen demand?

Answer 11

-Have a haemoglobin with a lower affinity for oxygen than human haemoglobin- dissociation curve is to right of ours