B - 2 - Haemoglobin

Question 1

What is haemoglobin?

Answer 1

An oxygen carrying protein found in red blood cells

Question 2

Describe the structure of haemoglobin

Answer 2

• Quaternary structure
• Has 4 polypeptide chains
• each chain has a haem group which contains an iron ion which gives haemoglobin its red colour

Question 3

How many molecules of oxygen can haemoglobin carry and why?

Answer 3

four, because each molecule binds to an iron ion, and there are for iron ions, one for each polypeptide chain

Question 4

What is oxyhemoglobin?

Answer 4

The molecule formed when oxygen binds to haemoglobin

Question 5

What is loading of oxygen (onto haemoglobin)

What is the other name for this process?

Answer 5

• The action of an oxygen molecule binding with a haemoglobin molecule
• Association

Question 6

What is unloading of oxygen (from haemoglobin)

What is the other name for this process?

Answer 6

The action of an oxygen molecule being released from a haemoglobin molecule

Question 7

What is affinity for oxygen?

Answer 7

The tendency a molecule has to bind with oxygen

Question 8

What is the partial pressure of oxygen?

Answer 8

A measure of oxygen concentration

Question 9

Describe the process that happens when there is a high partial pressure of oxygen

Answer 9

When there is a higher partial pressure of oxygen, oxygen loads onto haemoglobin to form oxyhaemoglobin

Question 10

Describe the process that happens when there is a low partial pressure of oxygen

Answer 10

Oxyhaemoglobin unloads it oxygen

Question 11

Describe what happens in terms of oxygen association in the alveoli?

Answer 11

• There is a high concentration of oxygen
• Therefore there is a high partial pressure
• So there is a high affinity
• So oxygen loads

Question 12

Why does association take place at the alveoli?

Answer 12

Because this is where oxygen enters the lungs

Question 13

Describe what happens in terms of oxygen dissociation in respiring tissues

Answer 13

• There is a low oxygen concentration
• Therefore a low partial pressure
• so there is a low affinity
• so oxygen unloads (dissociation)

Question 14

What is the Bohr effect

Answer 14

An affect by which an increase of carbon dioxide in the blood results in a reduction of haemoglobin affinity for oxygen

Question 15

What is the partial pressure of carbon dioxide?

Answer 15

A measure of carbon dioxide concentration

Question 16

How does carbon dioxide affect oxygen unloading?

Answer 16

When there is a higher partial pressure of carbon dioxide, haemoglobin gives up its oxygen more readily - dissociation takes place at a higher rate

Question 17

How do low oxygen environments effect haemoglobin and affinity

Answer 17

Organisms that live in low oxygen environments have haemoglobin with a higher affinity for oxygen

Question 18

How do high activity levels in organisms affect haemoglobin and association?

Answer 18

They have a lower affinity for oxygen as they need their haemoglobin to unload oxygen more easily so it is available for them to use

Question 19

How does the size of an organism affect haemoglobin and association?

Answer 19

Small mammals have a higher surface area to volume ratio than large animals so they lose heat quickly, so they have a high metabolic rate to keep them warm - so they have high oxygen demand. This means they have a lower affinity for oxygen as they need they haemoglobin to easily unload to meet their oxygen demand.

Question 20

Describe the placing of a dissociation curve of organisms in low oxygen environments in comparison to humans

Answer 20

Their dissociation curve is to the left

Question 21

Describe the placing of a dissociation curve of organisms with high activity levels in comparison to humans

Answer 21

Their dissociation curve is to the right

Question 22

Describe the placing of a dissociation curve of organisms that are small in comparison to humans

Answer 22

Their dissociation curve is to the right