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Hbc 100 Medical Biochemistry Question Paper

Hbc 100 Medical Biochemistry

Course:Bachelor Of Medicine And Bachelor Of Surgery

Institution: Moi University question papers

Exam Year:2007

M O I U N I V E R S I T Y

SCHOOL OF MEDICINE
END OF YEAR EXAMINATION (EYE) 2006/2007
COURSE TITLE: MEDICAL BIOCHEMISTRY
COURSE CODE: MBC 100
PROGRAMME: M.B.Ch.B. YEAR OF STUDY: 1 (ONE)
DATE: 6TH NOVEMBER, 2007 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 SHEET PROVIDED.

(III) A CORRECT RESPONSE EARNS YOU ONE MARK.

1. Glucuronic acid is formed when;

(a) Glucose is heated with strong H2SO4
(b) The aldehyde group of glucose is oxidized – gluconic acid
(c) The primary alcohol group of glucose is oxidized *
(d) Both aldehyde and alcohol groups of glucose are oxidized
(e) The primary alcohol group of glucose combine with H3PO4

2. The sedimentation velocity of a protein in a centrifuge does not depend o

(a) Density of the solution
(b) Density of the protein
(c) Charge on the protein
(d) Shape of the protein**??
(e) Mass of the protein

3. Which of the following amino acid will have its electophoretic properties changed by HCOOH?

(a) Cysteine
(b) Lysine*
(c) Hydroxylysine
(d) Tyrosine
(e) Threonine

4. Which of the following fatty acids has the lowest melting point?

(a) Linolenic acid*
(b) Propionic acid
(c) Caproic acid
(d) Butyric acid
(e) Linoleic

5. Organic cofactors of enzymes are commonly referred to as;

(a) Proenzymes
(b) Holoenzymes
(c) Apoenzymes
(d) Allosteric inducers
(e) Coenzymes**??

6. The process of protein synthesis involves all of the following except;

(a) Elongation *
(b) Hydroxylation
(c) Glycosylation
(d) Methylation
(e) Phosphorylation

7. All of the following are required for the DNA – dependent RNA polymerase reaction to produce RNA transcript except

(a) ATP
(b) CTP
(c) GTP
(d) Mg++
(e) UTP

8. Translation is involved in which of the following steps in the flow of genetic information?

(a) DNA to RNA
(b) RNA to DNA
(c) DNA to DNA
(d) RNA to protein *
(e) Protein to RNA

9. Primary transcripts are not;

(a) Larger than the final RNA molecules
(b) Made up of A,G, C, and U bases only
(c) Mature RNA molecules
(d) The immediate products of RNA synthesis
(e) Synthesized from a DNA template

10. In mismatch repair of DNA strand, discrimination is based on the action of;

(a) DNA helicase
(b) Dam methylase*
(c) DNA ligase
(d) DNA methyltransferase
(e) Exonuclease

11. Which of the following is not the function of Hb?

(a) To act as a blood buffer system
(b) To transport chemical messages in tissues *
(c) To bind and transport O2 to tissues
(d) To bind and transport protons to tissues
(e) To bind and transport CO2 from tissues

12. Sickle cell anemia occurs only if the following actions take place except;

(a) When a defective gene is inherited from both parents
(b) When HbS is produced
(c) Whenever RBC become hemolysed *
(d) When the sickling process is in progress
(e) When the blood is deprived of O2 by HbS

13. Which of the following molecular patterns or processes are common to both bacteria and humans except

(a) Genes are mosaics of nucleic acid sequence called introns and exons
(b) Nearly code
(c) Genetic information flow is the same
(d) Similar biomolecular composition
(e) The energy currency is the same

14. Condensation of two molecules of gamma aminolevulinic acid into porphobilinogen results in the elimination of;

(a) 2H2O *
(b) 3NH2
(c) 2CO2
(d) 2NH2
(e) 3H2O

15. Under normal conditions, chondroitin sulfate would not be found in;

(a) Blood vessels
(b) Synovial fluid *
(c) Cartilages
(d) Ligaments
(e) Tendons

16. Keratin is not characterized by its;

(a) High content of cystine in finger nails
(b) High content of lysine in human hair *
(c) High content of cystine in human hair
(d) Great insolubility in water
(e) Great resistance to attack by enzymes

17. The synthesis of hydroxyprogesterone is catalysed by;

(a) 17-Hydroxy dehydrogenase
(b) 17-Hydroxy hydroxylase
(c) 3-Hydroxy dehydrogenase
(d) 3-Hydroxy hydroxylase
(e) Lyase

18. Which of the following effects of PTH is directly mediated by an action of vitamin D metabolism?

(a) Activated adenylate cyclase
(b) Increased renal PO4 excretion
(c) Increased renal tubular reabsorption
(d) Decreased renal tubular reabsorption of PO4
(e) Increased intestinal absorption of Ca2+ *

19. Which of the following vitamins is essential for transketolase reaction?

(a) Pantothenic acid
(b) Folacin
(c) Niacin
(d) Riboflavin
(e) Thiamine

20. Which of the following is the main transporter of vitamin A in the body?

(a) Blood
(b) Plasma proteins
(c) Chylomicrons *
(d) CSF
(e) Low density lipoproteins

SECTION B: SHORT ANSWER QUESTIONS (SAQs) (60 minutes)

INSTRCUTIONS:

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.

SAQ 1. Explain the following properties of fatty acids;

(a) Melting point
(b) Solubility
(c) Geometrical isomerism

SAQ 2. With specific examples, describe briefly what isoenzymes are and highlight their clinical application.

SAQ 3. Using appropriate illustrations, highlight the differences between competitive and noncompetitive inhibitors of enzymes.

SAQ 4. Describe briefly the molecular basis of sickle cell hemoglobin.

SAQ 5. Using specific examples and illustrations, define in descriptive terms four basic structural levels of proteins.

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. Give a sequence of enzymatic reactions involved in the biosynthesis of gonadal hormones from cholesterol.

LEQ 2. Outline the stages involved in protein biosynthesis in a prokaryotic cell.

LEQ 3. Discuss the metabolic roles of riboflavin, pyridoxal phosphate and pantothenic acid.

LEQ 4. Describe in detail, the structural composition and the functions of collagen, elastin and keratin.

LEQ 5. Describe the sequence of enzymatic steps involved in the synthesis of heme from glycine.

Hbc 100 Medical Biochemistry Question Paper

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