Heamoglobin

Question 1

what are hemoglobin molecules?

Answer 1

• chemically similar molecules
• found in many organisms
• they are protein molecules
• their Quaternary structure that has evolved to make it efficient at loading oxygen under one set of conditions and unloading it at another

Question 2

what is the primary structure of a hemoglobin molecule?

Answer 2

-the sequence of amino acids in the four polypeptide chains

Question 3

what is the secondary structure of a hemoglobin molecule?

Answer 3

-each of the four polypeptide chains are coiled into a helix

Question 4

what is the tertiary structure of a hemoglobin molecule?

Answer 4

-each polypeptide chain is folded into a precise shape which helps it carry oxygen

Question 5

what is the Quaternary structure of a hemoglobin molecule?

Answer 5

• all four of the polypeptide chains are linked together to form an spherical molecule
• each polypeptide is associated with a haem group which contains a ferrous ion

Question 6

what is loading?

Answer 6

-haemoglobin associates with oxygen in the lungs

Question 7

what is unloading?

Answer 7

-haemoglobin dissociates with oxygen in the tissues

Question 8

what happens to haemoglobin with a high affinity for oxygen?

Answer 8

• takes up oxygen more easily

- release it less easily

Question 9

what happens to haemoglobin with a low affinity for oxygen?

Answer 9

• it takes up oxygen less easily

- releases it easily

Question 10

Which conditions leads to oxygen associated at gas exchange surfaces?

Answer 10

• high oxygen concentration
• low carbon dioxide concentration
• high affinity of haemoglobin for oxygen

Question 11

Which conditions leads to oxygen disassociated at respiring tissues?

Answer 11

• low oxygen concentration
• high carbon dioxide concentration
• low affinity of haemoglobin for oxygen

Question 12

When does haemoglobin bind more loosely to oxygen?

Answer 12

-when in the presence of carbon dioxide the new shape of the haemoglobin molecule binds more loosely to oxygen

Question 13

why are there different haemoglobins?

Answer 13

• haemoglobin comes in different forms because they have different properties
• each species produces haemoglobin with a slightly different amino acid sequence meaning each haemoglobin has different binding properties

Question 14

how does haemoglobin reach the requirements for transporting oxygen?

Answer 14

-it’s shape changes in the presence of certain substances

Question 15

what must haemoglobin do to be efficient at transporting oxygen?

Answer 15

• readily associate with oxygen at the gas exchange surface

- readily dissociate from oxygen at the tissues