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Examination Candidate Number: __________
Desk Number: __________
BSc Degree Examinations 2018-
Department :
BIOLOGY
Title of Exam:
Molecular Biology and Biochemistry Part I
Time Allowed:
1 hour and 30 minutes
Marking Scheme:
Total marks available for this paper: 50 The marks available for each question are indicated on the paper.
Instructions:
Answer all questions in the spaces provided on the examination paper Materials Supplied: CALCULATOR
For marker use only: Office use only:
1 2 3 4 5 6 7 Total as %
DO NOT WRITE ON THIS BOOKLET BEFORE THE EXAM BEGINS DO NOT TURN OVER THIS PAGE UNTIL INSTRUCTED TO DO SO BY AN INVIGILATOR
- a) A dilute solution contains a 3:1 molar ratio of base to acid with pKa = 6.3. Calculate the pH. (3 marks)
b) Convert 0.07 mol into μmol (1 mark)
The figure below shows the titration curve for Glutamic acid, an amino acid which has a CH 2 CH 2 COOH side chain.
Titration curve for Glutamic acid
c) Determine the isoelectric point (pI) for Glutamic acid. (1 mark)
c) Circle the nucleoside. (1 mark)
d) What does denaturation of dsDNA involve? (1 mark)
e) In the dNTP below, draw an arrow to the part of the molecule that you would modify to stop polymerisation from happening after incorporation of the dNTP into DNA and state what you would change this into. (2 marks)
f) Name the enzyme that removes the lagging strand RNA primers in prokaryotes during DNA replication. (1 mark)
- Hydrogen bonding is an important intermolecular force found within proteins.
a) Compare the pattern and the strength of hydrogen bonding in parallel and antiparallel beta sheets. (2 marks)
b) State two other types of intermolecular forces found within proteins. (2 marks)
The space above the line should be sufficient for your answer
Ramachandran plot 3 for poly(Proline) protein
b) Compare the data in plots 2 and 3 to the data shown in plot 1. Explain the differences seen. (2 marks)
The space above the line should be sufficient for your answer
- DCG is an important tripeptide (Asp-Cys-Gly) found in mouse cells.
Cys Gly Asp
a) Using the amino acid structures above, draw the structure of DCG. (1 mark)
b) On your structure, label the chiral centres. (1 mark)
c) Explain the overall charge of DCG at physiological pH. (2 marks)
The space above the line should be sufficient for your answer
b) In an enzyme-catalyzed reaction experiment, Vmax = 0.33 mol/sec and Km = 8 mM. Assuming the enzyme shows standard Michaelis-Menten kinetics, what is the rate of the reaction when [S] = 25 mM? (2 marks)
c) Briefly define Km and Vmax, then describe their dependence on enzyme concentration. (4 marks)
- a) What class of enzymes is used in biological washing powders to remove blood stains? (1 mark)
b) Describe what is meant by allosteric inhibition. (1 mark)
The space above the line should be sufficient for your answer
c) What aspects of the mechanism of the catalytic triad of chymotrypsin is considered acid-base catalysis? Explain your answer. (4 marks)
The space above the line should be sufficient for your answer
