Question

Question 8. A transmembrane protein uses a β barrel structure to span the cell membrane. How can amino acid mutations in a protein within this β barrel structure affect interactions with the membrane and why? (Up to 50 words)

Question 9. Haemoglobin is a protein that carries oxygen in our red blood cells. Sickle cell anaemia is a genetic disease in which Glu at position 6 of haemoglobin is mutated to a Val, rendering haemoglobin non-functional. (i) What type of amino acid change is this? (1 mark) (ii) Give one reason why this could affect the function of this protein. (1 mark)

Answer 1

8. Span cell membranes are commonly found in porins. Porins and other membrane proteins contains beta barrel in which hydrophobic residues oriented towards the exterior while hydrophilic residues oriented towards aquatic interior core.

Amino acid mutation in this protein affect the integrity and structure. It influence the function.

9. (i). It is due to missense mutation( point mutation in nucleotide). A codon is affected and it code different amino acid other than the original.(ii). Under low oxygen tension, it get polymerised and become sickle in shape. This affects the amount of hemoglobin transfer.