Haemoglobin

Question 1

Location

Answer 1

Red Blood Cells (erythrocytes)

Question 2

Adaptation

Answer 2

No nucleus:
-contains more haemoglobin

Biconcave shape:
-increase SA for rapid diffusion/absorption of oxygen

Question 3

STructure

Answer 3

Quaternary structured protein- made of 4 polypeptide chains

Each polypeptide chain contains a haem group containing an iron ion(Fe2+)which combines with oxygen

Question 4

How is oxygen transported

Answer 4

Haemoglobin in red blood cells carries/transports oxygen (as oxyhaemoglobin)

Haemoglobin can carry 4 oxygen molecules – one at each Haem group

Question 5

how is oxygen loaded

Answer 5

In the lungs, at a high pO2, haemoglobin has a high affinity for oxygen → oxygen readily associates with haemoglobin

Question 6

How is oxygen unloaded into the blood

Answer 6

At respiring tissues, at a low pO2, oxygen readily unloads / dissociates from haemoglobin as there is low affinity.

Question 7

oxygen dissociation curves

Answer 7

-At high pO2, haemoglobin is saturated with O2
-At low pO2, haemoglobin is less saturated with O2.

Question 8

0% saturation

Answer 8

Haemoglobin has a low affinity fro oxygen as the 1st oxygen molecule binds.

-So from 0% saturation an increase in pO2 results in a slow increase in saturation.

Question 9

25-75% saturation

Answer 9

After the 1st O2 molecule binds the tertiary structure of the haemoglobin changes in a way that makes it easier for the 2nd and 3rd oxygen molecule to bind too so at this point haemoglobin has high affinity for oxygen because more iron ions are revealed

-rate of increase in % saturation increases as pO2 further increases

Question 10

what happens when the 3rd molecule binds to haemoglobin

Answer 10

Haemoglobin becomes saturated as the shape changes in a way that makes it harder fro other molecules to bind too.

-So at high pO2 the rate increase in % saturation decreases

Question 11

Bohr effect

Answer 11

high concentration of CO2 results in an increase rate of unloading.

Question 12

Describe the effect of carbon dioxide concentration on the dissociation of oxyhaemoglobin

Answer 12

When rate of respiration is high e.g. during exercise → releases CO2

High pCO2 lowers pH and reduces haemoglobin’s affinity for oxygen as
haemoglobin changes shape

Increases rate of oxygen unloading

Oxygen dissociation curve for haemoglobin shifts to the right

Question 13

advantage of bohr effect

Answer 13

provides more oxygen for muscles/tissues for aerobic respiration as more dissociation of oxygen.

Question 14

Describe the result of a dissociation curve shifted to the left.

Answer 14

-Curve shifted left → haemoglobin has a higher affinity for oxygen

-More oxygen associates with haemoglobin more readily (in the lungs) at the lower pO2 BUT dissociates less readily

Question 15

advantages of a dissociation curve shifted to the left.

Answer 15

Advantageous to organisms such as those living in high altitudes, underground, or foetuses

Question 16

Describe the result of a dissociation curve shifted to the right.

Answer 16

Curve shifted right → haemoglobin has a lower affinity for oxygen

Oxygen dissociates from haemoglobin more readily to respiring cells at a higher
pO2 BUT associates less readily

Question 17

advantages of a dissociation curve shifted to the right.

Answer 17

Advantageous to organisms such as those with a high rate of respiration (metabolic rate) e.g. small / active organisms