Haemoglobin

Question 1

What do red blood cells contain?

Answer 1

Haemoglobin (Hb)

Question 2

What is hemoglobin?

Answer 2

A large protein with a quaternary structure (4)

it is made up of more than one polypeptide chain (four of them)

Question 3

What does affinity for oxygen mean?

Answer 3

Tendency to combine with oxygen

Question 4

What does each chain of the polypeptide of hemoglobin have?

Answer 4

Haem group which contains an iron ion

also gives haemoglobin its red colour

Question 5

Why does haemoglobin have a high affinity for oxygen?

Answer 5

Each molecule can carry four oxygen molecules

Question 6

How does haemoglobin become oxyhaemoglobin?

Answer 6

Oxygen joins to haemoglobin in red blood cells to form oxyhaemoglobin

Question 7

Diagram of reversible reaction

Answer 7

Oxygen leaves oxyhemoglobin (dissociates from it) near the body cells

turns back to haemoglobin

Question 8

What is the partial pressure of oxygen (pO₂)?

Answer 8

Measure of oxygen concentration

Question 9

What happens with partial pressure with the greater concentration of dissolved oxygen in cells?

Answer 9

It gets higher

Question 10

What is partial pressure of carbon dioxide (pCO₂) a measure of?

Answer 10

Concentration of CO2 in cell

Question 11

What does hemoglobin’s affinity of oxygen depend on?

Answer 11

Depending on the partial pressure of oxygen

Question 12

What happens if there is a high pO₂?

Answer 12

Oxygen loads onto haemoglobin to form oxyhaemoglobin

-because oxygen enters blood capillaries at alveoli at lungs. Alveoli have high pO₂ so oxygen does this to form oxyhaemoglobin

Question 13

What happens if there is a lower pO₂?

Answer 13

Oxyhameoglobin unloads its oxygen when there’s a lowe pO₂

_{- when cells respire, they use up oxygen lowering pO2 so red blood cells deliver oxyhaemoglobin to respiring tissues to unload its oxygen}

_{Haemoglobin returns to lungs to pick up more oxygen}

Question 14

What does a dissociation curve show?

Answer 14

How saturated the haemoglobin is with oxygen at any given partial pressure

Question 15

What does 100% and 0% mean in the saturation of hemoglobin with oxygen?

Answer 15

100% saturation: every haemoglobin molecule is carrying the max of 4 molecules of 02

0% saturation: means none of the haemoglobin molecules are carrying oxygen

Question 16

What happens when p02 is high (e.g in lungs)

Answer 16

Haemoglobin has higher affinity of oxygen (readily combine with oxygen so high saturation of oxygen)

Question 17

What happens when p02 is low? (e.g respiring tissues)

Answer 17

Haemoglobin has a low affinity for oxygen which means it releases oxygen rather than combines with it

Therefore, lower saturation of oxygen

Question 18

When does haemoglobin give up their oxygen more readily at?

Answer 18

A higher partial pressure of carbon dioxide (pCO2)

Question 19

Explain the Bohr Shift

Answer 19

1. When an organism respires a lot there is a lot of C02 in their blood (raises PCO2)
2. When there is more carbon dioxide, rises blood acidity
3. Higher blood acidity decreases hemoglobin affinity for O2
4. O2 unloads more easily at respiring cells
5. Haemologbin in less saturated with O2 because it has released more 02 at respiring cells

Question 20

What do different organism have?

Answer 20

Different types of hemoglobin with different oxygen transporting capacities

Type is an adaptation to survive in a particular environment

Question 21

Explain a high 02 envirnoment

Answer 21

• Haemoglobin has a lower affinty of 02
• Release more 02 at cells
• Useful for animals with high rate of respiration

Question 22

Why would small animals need to be in a high 02 environment?

Answer 22

• High surface area to volume raito
• Lose more heat per gram of body
• Maintain internal temperature

Question 23

Explain a low 02 environment

Answer 23

• Lower partial pressure of 02 in lungs
• Haeoglobin has a higher affinty of 02
• Able to load 02 at a lower partial pressure of 02

Question 24

Explain why the oxygen dissociation curve is S-shaped?

Answer 24

• Haemoglobin (Hb) combines with first 02 molecule
• shape alters so easier for other molecules to join too
• When Hb becomes saturated, harder for more O2 molecules to join
• Curve gets steep in middle when easy for 02 molecules to join (shallow - harder)
• Curve steep - small change of p02 causes big change in amount of 02 in Hb

Question 25

Hemoglobin is a protein with a quaternery structure

Explain what this means:

Answer 25

It is composed of more than one polypeptide chain

The fact it is made up of four polypeptide

Question 26

The graph shows the normal oxygen dissociation curve for human hemoglobin

(i) Sketch what you would expect in a high carbon dioxide environment
(ii) Earthworms live in a low oxygen environment, On graph sketch a curve

Answer 26