Past Paper Questions

Question 1

What are intermediate filaments made out of?

Answer 1

IFs are made up of polymerised, true fibrous filamentous subunit proteins which form rope-like filaments. 10-15nm diameter.

Question 2

What is inclusion cell disease?

Answer 2

Phosphotransferase (a Golgi enzyme) stops working so mannose-6-phosphate marker isn’t added to the proteins which need to be targeted to the lysosomes. Therefore, lysosomes cannot function properly and degrade substances.

Question 3

How do you distinguish between HbA and HbS?

Answer 3

The sixth position of a normal (HbA) beta chain has glutamate (negatively charged, more attracted to anode) whereas a sickle cell (HbS) beta chain has valine which is hydrophobic so hydrophobic interactions form within the blood cell, creating a sickle shape.
Haemoglobin electrophoresis is used - HbA cells travel further than HbS cells because the sickle cells clump together which increases mass.

Question 4

What would a mutation in genes at the splice sites affect the most?

Answer 4

They would affect the splicing of introns so one or more introns would be left in mature mRNA which would affect the synthesis of proteins.

Question 5

What is epigenetics?

Answer 5

The study of the heritable changes due to the modification of gene expression rather than alteration of the genetic code itself.

Question 6

What changes are seen with tuberculosis?

Answer 6

Granuloma formation.

Question 7

Describe the sequential action of the pyruvate dehydrogenase complex?

Answer 7

1. Decarboxylation of pyruvate (pyruvate decarboxylase/E1) followed by attack from the TPP carbanion to form hydroxyethyl TPP.
2. Oxidation and transfer to lipoamide to form acetyllipoamide.
3. Transfer of the acetyl group to CoA (lipoamide reductase transacetylase/E2) to form acetyl CoA.
4. Regeneration of oxidised lipoamide, which forms FADH2 (dihydrolipoyl dehydrogenase/E3).
5. Regeneration of oxidised FAD, generating NADH.

Question 8

What is the Mendelian Inheritance pattern for Haemophilia A and B, and which chromosome are the genes on?

Answer 8

X-linked recessive. Genes F8 and F9 on chromosome X.

Question 9

What is genomic imprinting?

Answer 9

Epigenetic phenomenon which causes genes to be expressed in a manner specific to their parent of origin.

Question 10

Genetic markers

Answer 10

Flags in the genome which enable us to study inheritance.

An ideal marker is highly polymorphic, randomly distributed, easily assayable and stable.

Question 11

How to reveal pathogenicity island?

Answer 11

Align pathogenic genomic DNA and a closely related non-pathogen.