The role of Haemoglobin in Oxygen Transport

Question 1

Explain the Adaptations of Red Blood Cells

Answer 1

-no nucleus increases surface area for diffusion of oxygen
-bioconcave shape increases surface area for diffusion of oxygen
-flat and thin which creates a short diffusion pathway for oxygen to reach all the haemoglobin inside

Question 2

Describe the simple structure of haemoglobin

Answer 2

Haemoglobin is a large protein with a quaternary structure, made of four polypeptide chains, and each chain has a heam group which contains an iron ion. Each molecule can bind too four oxygen molecules as oxygen binds to the heam group.

Question 3

what is formed when haemoglobin and oxygen associate / binds?

Answer 3

oxyhaemoglobin

Question 4

what is the name for oxyhaemoglobin releasing its oxygen to respiring cells?

Answer 4

dissociation

Question 5

what is partial pressure?

Answer 5

A measure of the concentration of that gas in a mixture of gas or liquid

Question 6

what conditions are dependent on haemoglobins affinity for oxygen

Answer 6

-partial pressure of oxygen
-haemoglobin saturation
-partial pressure of carbon dioxide

Question 7

what affect does partial pressure of oxygen have on haemoglobin affinity for oxygen?

Answer 7

• as the partial pressure of oxygen increases so does the affinity for oxygen
  -as the partial pressure of oxygen decreases so does the affinity for oxygen

Question 8

What is the cooperative nature of oxygen binding?

Answer 8

when the first molecule of oxygen binds too the haemoglobin and changes its tertiary structure this uncovers more haem binding sites so it is easier for additional molecules of oxygen to bind.

Question 9

Areas of high oxygen partial pressure:

Answer 9

-haemoglobin has a higher affinity for oxygen
- so oxygen associated with haemoglobin
-so the percentage saturation of oxygen is high

Question 10

areas of low oxygen partial pressure:

Answer 10

-haemoglobin has a lower affinity for oxygen
-so oxygen disassociates from haemoglobin
-so the percentage saturation of oxygen is low

Question 11

As partial pressure of carbon dioxide increases what happens toothed oxygen affinity of haemoglobin?

Answer 11

oxygen affinity drcreases as it is harder for oxygen to bind to the haem group of the haemoglobin

Question 12

what does the Bohr Effect suggest

Answer 12

the effect of carbon dioxide partial pressure on the disassociation curve- right shift

Question 13

how does the partial pressure of haemoglobin affect the affinity of haemoglobin for oxygen

Answer 13

when the partial pressure for carbon dioxide is high oxygen dissociated from haemoglobin more easily allowing more oxygen to be unloaded. This occurs as there is an increased production of carbon dioxide during respiration leading to a decrease in blood pH as it reacts with water to form carbonic acid, and low pH causes the tertiary structure of haemoglobin to alter.

Question 14

Binding of one molecule of oxygen to haemoglobin makes it easier for a second oxygen molecule to bind

Answer 14

the first oxygen binds causing a change in the tertiary structure of the haemoglobin which expose more oxygen binding sites

Question 15

explain why foetus in the womb have a higher affinity of oxygen compared to an adult human.
(left shift)

Answer 15

-foetal haemoglobin binds more easily and is also more reluctant to dissociate, which is important as foetal haemoglobin needs to steel oxygen away from the mother’s haemoglobin when passing in the placenta.

Question 16

explain why animals living in low oxygen environment have a higher affinity for oxygen compared to adult humans
(left shift)

Answer 16

there is a lower atmospheric pressure so there will be a low partial pressure of oxygen, so less oxygen avaliable therefore the haemoglobin has to be able to load more oxygen at a lower partial pressure for oxygen to make sure enough oxygen is absorbed.

Question 17

Explain why small organisms with high SA:V or organisms with high metabolic rate have a lower affinity of oxygen compared to adult humans.
(right shift)

Answer 17

Smaller mammals will lose heat more quickly so will have a higher metabolic rate to maintain there temp, so more respiration is needed therefore there is a greater oxygen demand so the haemoglobin needs to easily unload oxygen to meet their oxygen demand for a faster rate of respiration.