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Mbc 100_Medical Biochemistry Question Paper
Mbc 100_Medical Biochemistry
Course:Bachelor Of Medicine And Bachelor Of Surgery
Institution: Moi University question papers
Exam Year:2006
M O I U N I V E R S I T Y
SCHOOL OF MEDICINE
END OF YEAR EXAMINATION (EYE) 2005/2006
COURSE TITLE: MEDICAL BIOCHEMISTRY
COURSE CODE: MBC 100
PROGRAMME: M.B.Ch.B. YEAR OF STUDY: 1 (ONE)
DATE: 17TH OCTOBER 2006 TIME: 9..00 A.M. – 12.00 NOON
GENERAL INSTRUCTIONS:-
(i) Write your University Registration Number on every piece of paper you
use.
(ii) Do not write your names on any piece of paper you use.
(iii) This paper consists of twenty (20) Multiple Choice Questions (MCQs) to be answered in twenty (20 ) minutes; six (6) Short Answer Questions (SAQs) to be answered in sixty (60) minutes and five (5) Long Essay Question (LEQ) to be answered in one hundred (100) minutes.
(iv) The questions are set out in three (3) sections headed section I: MCQs,
section II: SAQs and section III: LEQs
(v) Read carefully the additional instructions preceeding each section.
SECTION I: MULTIPLE CHOICE QUESTIONS (MCQs)
(20 minutes)
TYPE III
INSTRUCTIONS:-
(I) EACH OF THE QUESTIONS IN THIS SUBSECTION CONSISTS OF A STATEMENT/QUESTION WHOSE MOST APPROPRIATE COMPLETION/ANSWER IS PROVIDED AMONG THE FIVE OPTIONS NUMBERED (a) - (e).
(II) FOR EACH QUESTION, SELECT THE MOST APPROPRIATE OPTION AND INDICATE BY PRINTING AN X IN THE APPROPRIATE BOX IN THE ANSWER SHEETS PROVIDED.
(III) A CORRECT RESPONSE EARNS YOU ONE MARK.
1. Condensation of glycine and succinyl CoA to form aminolevulinic acid (ALA) is catalyzed by
(a) ALA oxidase
(b) ALA synthase *
(c) Ferrochelatase
(d) ALA carboxylase
(e) Succinate dehydrogenase
2. Which of the following are not components of the structure of heme?
(a) Methyl groups
(b) Vinyl groups
(c) Acetate groups *
(d) Propionate groups
(e) Pyrrole rings
3. Which of the following lipoprotein fraction is a major component of plasma cholesterol?
(a) High density lipoproteins
(b) Intermediate density lipoproteins
(c) Chylomicrons
(d) Low density lipoproteins *
(e) Very low density lipoproteins
4. Under normal conditions, mucin glycoproteins would not be expected to be present in
(a) Serum *
(b) Gastrointestinal tract (GIT)
(c) Respiratory tract
(d) Female genital tract
(e) Saliva
5. Which of the following is not an example of a glycosaminoglycan?
(a) Chondroitin sulfate
(b) Neuraminate *
(c) Heparin sulfate
(d) Keratan sulfate
(e) Hyaluronate
6. The enzyme that links aminoacids to their cognate tRNA is
(a) Topoisomerase
(b) Transferase
(c) Aminoacyl-tRNA synthetase*
(d) Ligase
(e) Ribonuclease
7. Which of the following codons is an initiation codon?
(a) ACU Termination codons> UAG, UAA, UGA.
(b) CCA
(c) UGC
(d) UAA
(e) AUG*
8. Which of the following bases can replace thymine in RNA synthesis?
(a) Adenine
(b) Cytosine
(c) Uracil*
(d) Guanine
(e) Hydroxymethylcytosine
9. Which of the following is a termination codon?
(a) UAA*
(b) AAA
(c) UGC
(d) GAG
(e) AGU
10. The approximate number of nucleotides found in tRNA are
(a) 75
(b) 60
(c) 118
(d) 50
(e) 85***???
11. Pyridoxal phosphate is a coenzyme derived from
(a) Vit B2
(b) Vit B1
(c) Vit B6 *
(d) Vit B12
(e) Vit B3
12. Amino acids in solution at neutral pH are predominantly
(a) Un-ionized
(b) Zwitterions *
(c) Negatively charged only
(d) Postively charged only
(e) Non-polar
13. Which of the following lipids has a sugar residue?
(a) Sulfolipids*
(b) Phospholipids
(c) Triglycerides
(d) Lipoproteins
(e) Sphingolipids
Glycolipids(contain sugars):> Sulfolipid, ganglioside, cerebroside, proteolipid.
14. Which of the following is not a phospholipid?
(a) Phosphatidylserine
(b) Cerebroside *
(c) Lecithin
(d) Cephalin
(e) Phosphatidylglycerol
15. Sphingolipids are important for all of the following except:
(a) components of cell membranes
(b) components of myelin cells
(c) spinal cord membranes
(d) Components of nerve cell membranes
(e) Sources of acetylCoA*???
16. Which of the following is a steroid hormone?
(a) Glucagon - protein
(b) PTH - protein
(c) Thyroxine
(d) Epinephrine
(e) Cortisol *
17. Which of the following is a protein hormone?
(a) Estrogen
(b) Deoxycorticosterone
(c) DHEA
(d) Dopamine *
(e) Testosterone
18. Thiamine is a water soluble vitamin commonly referred to as
(a) Vitamin B3
(b) Vitamin B1 *
(c) Vitamin B5
(d) Vitamin B2
(e) Vitamin B6
19. Which of the following hormones is not formed from cholesterol?
(a) Aldosterone
(b) Cortisol
(c) Progesterone
(d) Thyroxine *
(e) Estrogen
20. Which of the following is a lipid-soluble vitamin?
(a) Niacin
(b) Biotin
(c) Retinol *
(d) Folic acid
(e) Pantothenic acid
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SECTION B: SHORT ANSWER QUESTIONS (SAQs) (60 minutes)
INSTRUCTIONS:
I) THERE ARE SIX (6) QUESTIONS IN THIS SECTION
II) ANSWER ALL THE SIX (6) QUESTIONS
III) START EACH QUESTION ON A FRESH PIECE OF PAPER OF THE BOOKLET.
SAQ 1. Define the term “Transcription” and give an outline of the four stages of RNA transcription in a prokaryotic cell.
SAQ 2. Provide the structures of three common phospholipids, their functions and location in the cell.
SAQ 3. Highlight any five functions of proteins and their role in the cell.
SAQ 4. Name four types of bonds that are responsible for maintaining the protein structure and explain their differences.
SAQ 5. List five classes of enzymes with a corresponding type of the reaction catalyzed by each class.
SAQ 6. Draw the structure of niacin and name two compounds that exhibit biologic activity of this vitamin. Give two reactions where this vitamin participates as a coenzyme.
SECTION III: LONG ESSAY QUESTIONS (LEQs) (20 minutes each)
(100 minutes)
INSTRUCTIONS:
I) THERE ARE FIVE (5) QUESTIONS IN THIS SECTION
II) ANSWER ALL THE FIVE (5) QUESTIONS
III) START EACH QUESTION ON A FRESH PIECE OF PAPER OF THE BOOKLET.
LEQ 1. Describe in detail, the pathways for the biosynthesis of heme and for its breakdown into various bile pigments.
LEQ 2. Outline the steps for the synthesis of adrenocortical hormones.
LEQ 3. Describe the molecular basis of sickle cell hemoglobin and sickle cell trait.
LEQ 4. Describe the chemical composition, occurrence and functions of:
(a) Plasma glycoproteins
(b) Mucin glycoproteins
(c) Proteoglycans
LEQ 5. Describe the effects of the following three types of inhibitors on enzyme-catalyzed reactions:
(a) Competitive inhibition
(b) Noncompetitive inhibition
(c) Uncompetitive inhibition
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