7.1- HAEMOGLOBIN

Question 1

What are the haemoglobins?

Answer 1

group of chemically similar molecules found in wide variety of organisms

Question 2

What kind of molecules are haemoglobins?

Answer 2

protein molecules

Question 3

What kind of structure do haemoglobins have?

Answer 3

quaternary structure

Question 4

Why has the haemoglobins evolved a quaternary structure?

Answer 4

make it efficient at loading oxygen under one set of conditions but unloading under different set of conditions

Question 5

What is the primary structure of haemoglobin?

Answer 5

sequence of amino acids in the four polypeptide chains

Question 6

What is the secondary structure of haemoglobin?

Answer 6

each of the polypeptide chains coiled into helix

Question 7

What is the tertiary structure of haemoglobin?

Answer 7

each polypeptide chain folded into precise shape- important factor in its ability to carry oxygen

Question 8

What is the quaternary structure of haemoglobin?

Answer 8

all four polypeptides linked together to form almost spherical molecules

Question 9

What is each polypeptide associated with in haemoglobin?

Answer 9

with a haem group

Question 10

What does the haem group of haemoglobin contain?

Answer 10

ferrous (Fe2+) ion

Question 11

What can each Fe2+ ion of the haem group in haemoglobin combine to?

Answer 11

can combine with single oxygen molecule, making total of 4 oxygen molecules that can be carried by single haemoglobin molecules in humans

Question 12

What is the process by which haemoglobin binds with oxygen called?

Answer 12

loading or associating

Question 13

Where does loading/associating happen in humans?

Answer 13

in the lungs

Question 14

What is the process by which haemoglobin releases it oxygen called?

Answer 14

unloading or dissociating

Question 15

Where does unloading/ dissociating happen in humans?

Answer 15

in tissues

Question 16

What does haemoglobin with a high affinity for oxygen do?

Answer 16

take up oxygen more easily, but release it less easily

Question 17

What does haemoglobin with a low affinity for oxygen do?

Answer 17

take up oxygen less easily, but release it more easily

Question 18

What is the role of haemoglobin?

Answer 18

transport oxygen

Question 19

What must haemoglobin do to be efficient at transporting oxygen? (2)

Answer 19

readily associate with oxygen at surface where gas exchange happens

readily dissociate from oxygen at those tissues requiring it

Question 20

How is haemoglobin able to readily associate + dissociate from oxygen?

Answer 20

it changes its affinity (chemical attraction) for oxygen under different conditions

Question 21

How does haemoglobin’s affinity for oxygen change?

Answer 21

its shape changes in presence of certain substances i.e. carbon dioxide

Question 22

What happens to haemoglobin in the presence of carbon dioxide?

Answer 22

new shape of haemoglobin molecules binds more loosely to oxygen
so haemoglobin releases its oxygen

Question 23

Are there different types of haemoglobin?

Answer 23

yes

Question 24

Why do different haemoglobins have different affinities for oxygen?

Answer 24

lies in shape of molecules

Question 25

What is different about the haemoglobin of each species?

Answer 25

different tertiary + quaternary structure and hence different oxygen binding properties