Haemoglobin

Question 1

What reaction joins the monomers together?

Answer 1

Condensation reaction- peptide bonds

Question 2

What is the quaternary structure?

Answer 2

One or more polypeptide chains

Question 3

What is the prosthetic group?

Answer 3

Not made of amino acids- associated with the polypeptide chain- the binding site

Question 4

Adaptions of red blood cells?

Answer 4

Biconcave shape- larger SA for short diffusion distance
No nucleus- more space for HB
Contains haemoglobin- binds and carries O2
Small (7 micrometers)- larger SA:V ratio

Question 5

What does each chain of haemoglobin have?

Answer 5

A haem group- contains an iron ion and gives haemoglobin its red colour

Question 6

Does HB have a high or low affinity for O2?

Answer 6

High

Question 7

How many oxygen molecules can each HB molecule carry?

Answer 7

4

Question 8

What does affinity for oxygen mean?

Answer 8

The tendency to combine with oxygen

Question 9

Why do we need haemoglobin?

Answer 9

At body temperature, we have low solubility
So therefore we need a way to increase O2 transport

Question 10

What is the partial pressure of a gas?

Answer 10

The pressure a particular gas contributes to the total pressure of the gas mixture

Question 11

What is the partial pressure of oxygen?

Answer 11

A measure of oxygen concentration

Question 12

The higher the concentration of dissolved O2 in cells?

Answer 12

The higher the partial pressure

Question 13

What does the affinity for oxygen vary on?

Answer 13

The partial pressure

Question 14

When does oxygen load onto haemoglobin and what does it form?

Answer 14

Forms oxyhaemoglobin when there is a high partial pressure

Question 15

When does oxyhaemoglobin unload oxygen?

Answer 15

When there is a lower partial pressure

Question 16

Where is partial pressure the highest out of: alveoli, resting tissue and in muscles?

Answer 16

In alveoli because oxygen enters blood capillaries at the alveoli to form oxyhaemoglobin

Question 17

Why is partial pressure lowest in muscles?

Answer 17

Because when cells respire, they use up oxygen which lowers the partial pressure. Red blood cells deliver oxyhaemoglobin to respiring tissues, where it unloads its oxygen
The haemoglobin then returns to the lungs to pick up more oxygen

Question 18

What is the T state?

Answer 18

Tense
Haem groups are tucked away in the proteins

Question 19

What is the R state?

Answer 19

Conformational change- haem groups are more exposed to
Easier for 2nd, 3rd, 4th O2’s to bind

Question 20

What do dissociation curves show us?

Answer 20

How saturated the haemoglobin is with O2 at any given partial pressure

Question 21

What does 100% saturation mean?

Answer 21

Every haemoglobin is carrying the maximum of 4 molecules of O2

Question 22

What does 0% saturation mean?

Answer 22

None of the haemoglobin molecules are carrying any oxygen

Question 23

Explain why partial pressure is high and so is saturation?

Answer 23

Where partial pressure is high (e.g. in the lungs), haemoglobin has a high affinity for oxygen- will readily combine- therefore there is a high saturation of O2

Question 24

Explain why partial pressure is low and why saturation is also low?

Answer 24

Where pO2 is low (e.g. respiring tissues), haemoglobin has a low affinity for oxygen- will release oxygen instead of combining with it- therefore there is a low saturation

Question 25

Why is the graph S shaped?

Answer 25

When haemoglobin combines with the first oxygen molecule, its shape alters in a way that makes it easier for other molecules to join too But as haemoglobin starts to become saturated, its harder for more oxygen molecules to join The curve has a steep bit in the middle where it is easy for oxygen molecules to join and shallow bits where its harder When the curve is steep a small change in pO2 causes a big change in the amount of oxygen carried by haemoglobin.

Question 26

How is carbon dioxide transported in the blood?

Answer 26

5% in solution in the blood 25% binds to haemoglobin- forms carbohaemoglobin (undergoes a slight shape change) 70%- forms carbonic acid

Question 27

Do haemoglobonic acid and carboamino haemoglobin have a lower or higher affinity for oxygen?

Answer 27

Lower affinity for oxygen Harder for oxygen to bind Easier for oxygen to unbind

Question 28

What is the Bohr effect?

Answer 28

A fall in pH reduces the affinity of Hb for O2 Causes increased unloading of O2 from Hb at any partial pressure of oxygen As rate of reaction increases and partial pressure of carbon dioxide increases, you get rapid unloading of oxygen due to the Bohr effect- there is plenty of oxygen for aerobic respiration which means that less lactic acid is produced

Question 29

Does fetal Hb have a higher or lower affinity for oxygen?

Answer 29

Higher affinity Allows oxygen to unload from maternal haemoglobin and load the fetal haemoglobin

Question 30

Does myoglobin have a high or low affinity for oxygen?

Answer 30

High affinity Oxygen stays bound unless partial pressure of oxygen is very low- then it unloads rapidly which delays anaerobic respiration

Question 31

Is there lower or higher partial pressure of oxygen in high altitudes?

Answer 31

Lower partial pressure- is harder for collisions

Question 32

Does llama haemoglobin have a higher or lower affinity for oxygen?

Answer 32

Higher affinity Easier for oxygen to bind at low partial pressures of oxygen (increased loading) Unloading occurs at lower partial pressures of oxygen

Question 33

What conditions do lugworms live in?

Answer 33

Anoxic (very low oxygen) conditions Live in muddy estuaries Oxygen is less soluble in water

Question 34

In anoxic conditions what is loading and unloading like?

Answer 34

High affinity for oxygen- loading occurs at very low oxygen Unloading occurs at low partial pressures in tissues

Question 35

Elephant?

Answer 35

Hb has a higher affinity for oxygen- lower SA:V ratio Slower rate of heat loss Slower metabolic rate Having a higher affinity of Hb for oxygen is beneficial- ensures oxygen is not unloaded too quickly

Question 36

Mouse?

Answer 36

Hb has a lower affinity for oxygen- higher SA:V ratio Slower Faster rate of heat loss More active Faster metabolic rate Lower affinity of Hb for oxygen enables more rapid unloading