2.3.5 Haemoglobin

Question 1

What is the type of protein a hemoglobin is?

Answer 1

globualr

Question 2

Why hemoglobin has a quaternary structure?

Answer 2

there are four polypeptide chains/subunits are globin proteins (two a-globin and two B-globin)

Question 3

What is the prosthetic group of hemoglobin?

Answer 3

haem

Question 4

Briefly describe the structure of hemoglobin

Answer 4

• four globin subunits held by disulphide bonds
• hydrophobic R group facing inwards (helping preserve the three dimensional spherical shape)
• hydrophilic R groups facing outwards (solubility)

Question 5

How sickle cell anemia occurs?

Answer 5

valine (non-polar) replaces glutamic acid (polar) in the amino acids in the B-globin making it less soluble

Question 6

What causes the bright color of blood?

Answer 6

when Iron Fe2+ in the prosthetic group in the heam group binds with oxygen forming oxyhaemoglobin

Question 7

How many oxygen atoms each haemoglobin can hold?

Answer 7

four haemoglobin carry two oxygen atoms each (8 atoms of oxygen)

Question 8

Describe the importance of haemoglobin

Answer 8

-oxygen is not very soluble alone
- presence of the haem group and Fe2+ enables oxygen to be bound more easily as each oxygen molecule binds it alters the quaternary structures of the proteins