Haemoglobin

Question 1

How do organisms carry oxygen to their cells?

Answer 1

in the blood via haemoglobin

Question 2

What is special about haemoglobin?

Answer 2

it can have many variations for different organisms to fit their environments

Question 3

Why don’t red blood cells have a nucleus?

Answer 3

to leave space for haemoglobin

Question 4

What is haemoglobin?

Answer 4

a globular protein made up of 4 polypeptide chains

Question 5

What level of structure does haemoglobin have?

Answer 5

a quaternary structure

Question 6

What are the chains at the top of haemoglobin called?

Answer 6

alpha chains

Question 7

What are the chains at the bottom of the haemoglobin called?

Answer 7

beta chains

Question 8

What does a fully saturated haemoglobin have?

Answer 8

all 4 oxygen molecules bound to the haem groups

Question 9

What does a high oxygen affinity mean?

Answer 9

it wants to/has a tendency to bind to O2

Question 10

What is pO2? (i.e in the alveoli)

Answer 10

partial pressure of oxygen (how much oxygen there is)

Question 11

What is partial pressure measured in?

Answer 11

kPa

Question 12

What happens at the gas exchange surfaces (at the alveoli) with haemoglobin?

Answer 12

haemoglobin has a high affinity for O2, so the O2 binds readily

Question 13

What happens at the respiring tissues with haemoglobin?

Answer 13

haemoglobin has a low affinity for O2, as the high concentration of CO2 causes the haemoglobin to change shape, which releases the oxygen

Question 14

What shape is the oxygen dissociation curve?

Answer 14

S-shaped

Question 15

Why is the oxygen dissociated curve shaped in this way? Explain each region of it

Answer 15

initial slow increase of pO2 as it is slightly more difficult for the first molecule of O2 to bind to the Hb

then pO2 increases quickly as after the first O2 has bound it slightly distorts the Hb protein which makes it much easier for the second and third O2 to bind

finally pO2 slows down again as it is more difficult for the fourth O2 to bind

Question 16

What happens to Co2 levels when the rate of aerobic respiration increases, and what does this mean?

Answer 16

the CO2 levels go up, and this CO2 dissolves to form carbonic acid

Question 17

What does carbonic acid do to the haemoglobin?

Answer 17

carbonic acid changes the blood pH and this affects the haemoglobin; they lose oxygen more readily- this shifts the oxygen dissociation curve to the RIGHT

Question 18

What is the Bohr effect and why is it a good thing during exercise?

Answer 18

-haemoglobin gives up it’s oxygen more readily at a higher pCO2
-during activity there is a higher respiratory rate which increases the production of CO2- this leads to increased carbonic acid levels in blood which lowers the blood pH- this means that haemoglobin more readily gives up it’s oxygen which is an an advantage during exercise as your cells need more oxygen

Question 19

Which way does the Bohr effect shift the oxygen dissociation curve?

Answer 19

TO THE RIGHT

Question 20

What factors result in the Bohr effect?

Answer 20

-blood temperature
-blood pH
-CO2 concentration

Question 21

Why do different animals have variation in their haemoglobin?

Answer 21

to fit their habitats- they have different sequences of amino acids

Question 22

What is myoglobin?

Answer 22

a molecule with a similar structure to haemoglobin but only has 1 haem group instead of 4; it also has a very very high affinity for oxygen even at very low pO2

Question 23

What is the myoglobin oxygen dissociation curve like compared to the haemoglobin oxygen dissociation curve?

Answer 23

it looks like an inverted L shape as it stays saturated for longer with a very steep decrease/increase

Question 24

What type of mammals generally have more myoglobin?

Answer 24

diving mammals

Question 25

When does the oxymyoglobin dissociate?

Answer 25

when the oxygen levels are very low

Question 26

Where is myoglobin found?

Answer 26

myoglobin is found in muscle cells where it acts as an oxygen reserve (good oxygen storage)

Question 27

Why does foetal haemoglobin have a higher oxygen affinity than the mothers haemoglobin?

Answer 27

the mother is using some of her own haemoglobin which means for the foetus there is less, so it's haemoglobin needs to get fully saturated in a lower pO2, so foetus haemoglobin has a higher affinity for oxygen

Question 28

If the oxygen dissociation curve is to the left, what does this mean about the Hb?

Answer 28

the haemoglobin is more easily saturated with oxygen

Question 29

If the oxygen dissociation curve is to the right, what does this mean about the Hb?

Answer 29

the haemoglobin more readily releases oxygen to tissues

Question 30

Why do lugworms have haemoglobin that has a high affinity for oxygen?

Answer 30

because they live in burrows beneath sand where there's a low oxygen concentration

Question 31

Why do mice have haemoglobin that has a lower affinity to oxygen?

Answer 31

because they have a larger surface area to volume ratio than a human-they lose heat quickly so have a high metabolic demand so need to be able to unload oxygen easily to meet oxygen demand

Question 32

Why is having more red blood cells an advantage at higher altitudes?

Answer 32

-at higher altitudes there is a lower partial pressure of oxygen -more red blood cells mean more haemoglobin -so more haemoglobin can bind more oxygen for use in respiration