Albinism is

a genetic disorder that results due to the inability of melanocytes to

synthesise melanin, a pigment found in skin, hair and eyes.

Defects in

converting which amino acid to melanin have been associated with albinism?

The

coding region of a gene is 303 nucleotides long, including the start and stop

codons. A mutation is detected in a patient, in which nucleotide 100 is mutated

from an A to a T. This mutation results in a stop codon at that position.

How

many amino acids will there be in the protein expressed in the patient’s cells?

A 6 year old boy is brought to the physician by his

parents because he experiences abdominal pain after eating a high-fat meal.

After running several tests, the boy is diagnosed with a deficiency of the

enzyme lipoprotein lipase.

Which of the following is an example of a reaction

catalysed by lipoprotein lipase?

A 4 year old girl presents with metabolic acidosis, failure to thrive and developmental delay. After extensive investigation and DNA analysis, she is diagnosed with pyruvate carboxylase deficiency.

What vitamin is necessary for the proper functioning of pyruvate carboxylase?

The recommended dietary allowance for vitamin B

6

Deficiency of vitamin B₆

will result in

decreased concentrations of which of the following?

A 27 year old man presents to the Accident and Emergency Department saying that he thinks he is having an allergic reaction to the fava beans he consumed for the first time in his life earlier in the day.   The physician suspects that the patient has glucose 6-phosphate dehydrogenase deficiency (G6PD) which was asymptomatic until the consumption of fava beans which triggered the favism observed.  Upon investigation, the patient also has hemolytic anaemia.

 Which of the following explanations best describe why hemolytic anaemia is observed in patients with G6PD?

A 46 year old female presents to the physician with

a burning sensation upon urination. Following several tests, she is diagnosed

with a bladder infection and the antibiotic trimethoprim is prescribed.

A 4 year old boy presents to a physician with

neurodegeneration, hepatosplenomegaly and a macular cherry-red spot. The

physician suspects that the most likely underlying cause of these symptoms is

Niemann-Pick disease and she refers the child to a clinical geneticist. In

order to confirm the diagnosis, the clinical geneticist requests DNA sequencing

of the gene which encodes the enzyme which is defective in Niemann-Pick

disease.

A researcher

performed a restriction fragment length polymorphism (RFLP) experiment to

identify the presence of a G or a C in a specific locus of the human genome. To

do this he performed a polymerase chain reaction (PCR) experiment to amplify a

250 bp PCR product. An enzyme called A2B was then used to digest the PCR

product. If a G was present at the specific location of interest the PCR

product would be cleaved into two fragments of 150 bp and 100 bp. If a C was

present, the PCR product would remain intact. The results are shown in Figure 1

below.

Figure 1:

  Agarose gel

showing RFLP results after restriction of a PCR product.

The ligand found in rhodopsin is 11-cis

retinaldehyde. Activation of

rhodopsin occurs when light converts

Which vitamin consists of a group of molecules that

includes the rhodopsin ligand?