Haemoglobin

Question 1

what are the haemoglobins?

Answer 1

a group of chemically similar molecules found in a wide variety of organisms

Question 2

haemoglobin is globular - what does this mean?

Answer 2

round
compact
easily soluble

Question 3

the haemoglobin structure is curled up - what does this mean?

Answer 3

the hydrophillic side chains face inwards.

this makes the molecule soluble so good for transport in the blood

Question 4

finish the equation:

Hb + 4O2

Answer 4

4Hb(O2)

Question 5

what is the tertiary structure of haemoglobin?

Answer 5

each polypeptide chain is folded into a precise shape for carrying oxygen

Question 6

what is the quaternary structure of haemoglobin?

Answer 6

4 polypeptides linked together to form an almost spherical molecule

Question 7

what is each polypeptide in haemoglobin associated with?

Answer 7

a haem group

Question 8

what does a haem group contain?

Answer 8

Fe 2+

Question 9

what can each Fe 2+ combine with?

What does this mean?

Answer 9

O2

4 O2s can be carried by one haemoglobin molecule

Question 10

define partial pressure

Answer 10

a measure of the concentration of a gas, taking into account air pressure
e.g. high pO2 in lungs, low pO2 in muscles

Question 11

define affinity

Answer 11

the tendency of a chemical substance to react with another chemical substance

Question 12

what does haemoglobin’s affinity for oxygen depend on?

Answer 12

pO2

Question 13

how does O2 bind in a high affinity?

Answer 13

easily

Question 14

define loading/association in terms of haemoglobin

Answer 14

O2 associates with haemoglobin to form oxyhaemoglobin when there is a high pO2

Question 15

define unloading/dissociation in terms of haemoglobin

Answer 15

O2 unloads from oxyhaemoglobin when there is a low pO2

Question 16

define saturation in terms of haemoglobin

Answer 16

how much oxygen is being carried (%)

Question 17

Finish the sentence:

Haemoglobins with a high affinity for oxygen…

Answer 17

take up oxygen more easily, but release it less easily

Question 18

Finish the sentence:

Haemoglobins with a low affinity for oxygen…

Answer 18

take up oxygen less easily, but release it more easily

Question 19

what is the role of haemoglobin?

Answer 19

to transport oxygen

Question 20

how is haemoglobin efficient at transporting oxygen?

Answer 20

readily associates with oxygen at the gas exchange surfaces

readily dissociates from oxygen at tissues requiring oxygen

Question 21

what allows both dissociation and association?

Answer 21

a change in affinity

Question 22

what aspect of how haemoglobin binds with oxygen makes it a good transporter?

Answer 22

it binds reversibly

Question 23

where in the body has a high pO2?

Answer 23

gas exchange surfaces

Question 24

where in the body has a low pO2?

Answer 24

respiring tissues

Question 25

what is haemoglobin like in other species?

Answer 25

different species have different amino acid sequences so slightly differently shaped haemoglobins. This affects the affinity