Haemoglobin

Question 1

What is haemoglobin

Answer 1

Protein

Question 2

What is it’s structure

Answer 2

Quaternary

4 polypeptides linked together to form 1 molecule

Question 3

What does each chain have that binds to oxygen to carry it

Answer 3

A haem group containing a ferrous iron (Fe2+ ion)

Question 4

How does haemoglobin tertiary structure allow it to bind to oxygen

Answer 4

Gives it its specific shape

Question 5

What problem are pigments like haemoglobin used to overcome

Answer 5

The low solubility of oxygen in water e.g dissolving in blood

Question 6

How many binding sites does haemoglobin have to carry oxygen

Answer 6

4

Question 7

What is the binding of oxygen called

Where does this take place

Answer 7

Loading/associating

In the lungs

Question 8

What’s the process where haemoglobin releases oxygen called

Where does this take place

Answer 8

Unloading/dissociating

Tissues

Question 9

What affinity would haemoglobin have if it could take up oxygen easily but release it less easily

Answer 9

High

Question 10

Describe haemoglobin with low affinity

Answer 10

Take up oxygen less easily

Release oxygen easily

Question 11

Describe how the 4 polypeptide chains cooperate to bind with oxygen

Answer 11

1. Oxygen binds to haem group of 1st polypeptide
2. Triggers a change in shape of other 3
3. Change in shape increases their oxygen affinity

Question 12

What’s % saturation

Answer 12

% of haemoglobin that has oxygen bound to its haem group

Question 13

What tissues have least % saturation

Answer 13

Heavily respiring - 3 oxygen may be released from each haemoglobin

Question 14

What are gas concentrations expressed as

Answer 14

Partial pressures (kPa)

Question 15

What is the product called in the lungs when oxygen and haemoglobin bind

Answer 15

Oxyhaemoglobin

Question 16

What surroundings is haemoglobin more likely to dissociate in
Why

E.g

Answer 16

Low oxygen levels
Due to increased CO2 levels

E.g repairing tissues (muscles)

Question 17

What’s the graph that shows the loading and unloading

Answer 17

The dissociation curve

Question 18

What areas does haemoglobin associate with oxygen

E.g

Answer 18

High levels of oxygen areas

E.g gas exchange surfaces, lungs

Question 19

What areas does haemoglobin dissociate from oxygen

E.g

Answer 19

Low oxygen areas

E.g respiring tissue

Question 20

What do oxygen dissociation curves show at the start

Answer 20

There is initially a slow uptake of haemoglobin

Question 21

Why is there initially a slow uptake by haemoglobin at start

Answer 21

As the shape makes it difficult for oxygen to bind at first

4 polypeptide chains are close together

Question 22

After the 1st oxygen molecule has bound what allows the oxygen molecules to bind easier

Answer 22

The conformational change (positive cooperativity)

Question 23

What is the graph like when there is positive cooperativity

Answer 23

Steep

Question 24

What happens to rate of saturation when 3rd oxygen molecule binds
Why

Answer 24

Slows down

As there’s only 1 binding site left on the haemoglobin so probability of binding is lower

Question 25

What happens to the graph when the 3rd molecule of oxygen has bound

Answer 25

Slows and flattens off

Question 26

Which way does the graph shift is its high affinity

Answer 26

Left and higher

Question 27

Which way does the graph shift is its low affinity

Answer 27

Right , lower

Question 28

3 factors that can effect unloading of oxygen

Answer 28

Temperature CO2 pH level

Question 29

What is a change to the dissociation curve due to CO2/pH called

Answer 29

The Bohr Shift

Question 30

When gas exchange surfaces have low CO2 levels what happens to the affinity for O2 e.g in lungs What does the graph do

Answer 30

Increases | Higher left

Question 31

What happens to affinity if CO2 levels are higher | What does the graph do

Answer 31

Decreases | Lower, right

Question 32

What does CO2 form when it diffuses into plasma from rbc’s and dissolves (pH)

Answer 32

Carbonic Acid

Question 33

What releases when CO2 forms carbonic acid

Answer 33

Releases H+ ions that will bind to haemoglobin and cause oxygen to be released

Question 34

What do H+ ions do to blood ph

Answer 34

Decrease it

Question 35

What does a lower blood pH cause (loading/unloading)

Answer 35

Increase in unloading of oxygen

Question 36

What does ph do when respiring

Answer 36

Drops (more acidic)

Question 37

What’s the Bohr affect caused by

Answer 37

Increase in CO2

Question 38

What happens in the Bohr affect

Answer 38

Increase in CO2 so more demand for oxygen Muscles need more oxygen for aerobic respiration Unload oxygen easier from haemoglobin to meet demand

Question 39

What does oxygen balance out

Answer 39

Carbonic Acid

Question 40

How does a lot of respiration cause oxygen to become available

Answer 40

``` More CO2 in tissues Lower ph Greater haemoglobin change Oxygen more readily dissociated So more available for respiration ```

Question 41

What catalyses CO2 + H2O in RBCs

Answer 41

Carbonic anhydrase

Question 42

Where do the HCO3- ions go when carbonic Acid is broken down | What does this do to red blood cells

Answer 42

Into plasma | Gives them a positive charge

Question 43

What is red blood cells positive charge counteracted by | What’s this called

Answer 43

Cl- entering RBC | called the chlorine shift

Question 44

What’s the affinity of foetal haemoglobin like | Why

Answer 44

High | As pp of oxygen is much lower in womb than lungs

Question 45

What are animals that live in high altitudes (llama) adapted to Where is curve

Answer 45

Adapted to bind more oxygen at lower partial pressures | Curve is at high affinity - High, left

Question 46

What size mammals have a lower oxygen affinity | Why

Answer 46

Smaller mammals e.g mouse Have larger SA:volume ratio so they lose heat fast. Have higher respiratory rate to keep themselves warm when needed so allow oxygen to be unloaded easily at respiring tissues

Question 47

What is myoglobin | What is its job

Answer 47

Found in muscle tissue | Jon is to bind any oxygen that is released by haemoglobin in the blood

Question 48

2 factors that cause variation in haemoglobin

Answer 48

Variations in primary structure - different amino acid sequences Adaptations to environmental conditions e.g different partial pressures of oxygen

Question 49

What is the condition that causes red blood cells to change shape due to variations in haemoglobin increasing risk of blood clots

Answer 49

Sickle cell anaemia