1. A mixture of alanine and alpha-ketoglurate is incubated with an enzyme named glutamatepyruvate transaminase (including the co-factor). After some time, the mixture is re-annalyzed
and two additional compounds are found to be present. What are these compounds? Write the
reaction taking place (structures not necessary).
(4)
2 Is tyrosine considered an essential amino acid for individuals with phenylketonuria? Explain
(3)
3 Consider the reaction shown below and answer the questions that follow.
(a) Name the enzyme that catalyzes this reaction.
(1)
(b) Name the substrate and product indicated by the structures.
(2)
(c) Which molecule is substrate X derived from?
(1)
4 How does the level of glutamic acid affect the urea cycle?
(3)
Indicate the mechanism of sulfonamide antibiotics. Also explain why they do not affect humans
the same way they do bacteria.
(5)
5 Differentiate between a glucogenic amino acid and ketogenic amino acid
(2)
6 Mammals detoxify ammonia by converting it into urea using the urea cycle. Answer the
following questions with regard to the urea cycle
a)
Write down the reaction for the synthesis of carbamoyl phosphate
(3)
b)
Name the two non-standard amino acids that are involved in the urea cycle
(1)
c)
Briefly describe the nature of the link between the urea cycle and the citric acid cycle (1)
7 Consider the figure below and answer questions that follow.
(a Which molecule is considered the end product of the pathway?
(1)
(b The reactions of this pathway occur in which part of the cell?
(2)
(c Which molecule is one of the 20 standard amino acids?
(1)
8 Briefly describe tetrahydrofolate (THF) with regard to
a) Metabolic source of THF
(1)
b) Role of THF in the biosynthesis of amino acids
(2)
9 Write short notes about the glucose alanine cycle
(3)
10 What is the main difference between the biosynthesis of purine molecules and the
biosynthesis of pyrimidine molecules
(2)
11 Both the salvage and de novo synthesis pathways of purine and pyrimidine biosynthesis lead
to the production of nucleoside-5′-phosphates through the utilization of an activated sugar.
Provide a name for this activated sugar.
(1)
12 What is the end product of purine degradation and why is this compound potentially
problematic?
(2)