PWNI I'IHITIIBIH UI'IIVERSITY. (Including this front page) SUPPLEMENTARY/SECOND OPPORTUNITY QUESTION PAPER FACULTY OF HEALTH AND APPLIED SCIENCES

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1 I. I'IHITIIBIH UI'IIVERSITY 0F SCIEI ICE HUD TECHNOLOGY FACULTY OF HEALTH AND APPLIED SCIENCES DEPARTMENT OF NATURAL AND APPLIED SCIENCES QUALIFICATION: BACHELOR OF SCIENCE QUALIFICATION CODE: O7BOSC LEVEL: 7 COURSE CODE: BPP7025 COURSE NAME: BIOCHEMISTRY: BIOCHEMICAL PRINCIPLES AND PRACTICE SESSION: JANUARY 2018 PAPER: THEORY DURATION: 3 HOURS MARKS: 100 SUPPLEMENTARY/SECOND OPPORTUNITY QUESTION PAPER EXAMINER MODERATOR: DR LAM ECH MWAPAG HA DR PETRINA KAPEWANGOLO PWNI INSTRUCTIONS Answer ALL the questions. Write clearly and neatly. Number the answers clearly. All written work MUST be done in BLUE or BLACK ink. PERMISSIBLE MATERIAL Scientific Calculator THIS QUESTION PAPER CONSISTS OF FIVE (5) PAGES (Including this front page)

2 QUESTION 1 [7] a) Briefly, discuss how does hydrogen bonding occurs between molecules of water. (2) b) With the knowledge of the structure of water, explain why water in solid form is lighter than in its liquid form. (5) QUESTION 2 [14] a) Calculate the pka of lactic acid, given that when the concentration of free lactic acid is 0.01M and the concentration of lactate is 0.087M, the ph is (4) b) A buffer solution contains 0.25 M NH3 (Kb: 1.8 x10'5) and 0.40 M NH4CI. Calculate ph of this solution. (4) (a) Given the structures of lysine and the pka values as shown below: (6) H H *l N CIZ C cl; \ 90 I \ OH Lysine PK. = : = 8.95 pka: = Determine the pl value of lysine. Show clearly how you arrive at the answer.

3 QUESTION 3 [18] a) Draw the Haworth projection of the monosaccharide below in the on and [3 forms. (6) CHO H C OH Ho cl w-i H - <l: 0H H (lz- OH (IZHZOH b) Three different disaccharides are shown in the figure below H0 503,05 8CH,OH o 5 5 some}: o H OH H OH Lactose Maltose Sucrose I. Name the monosaccharides that these disaccharides are composed of indicating their stereoisomer form. (6) 1. Lactose: 2. Maltose: 3. Sucrose: ll. Which of these disaccharides (if any) contain; (6) 1. an aldose 2. a pyranose 3. afuranose 4. aribose 5. aketose 6. al stereoisomer

4 QUESTION 4 [12] a) A biosynthetic pathway proceeds from compound A to compound E in four steps and then branches. One branch is a two-step pathway to G, and the other is a three-step pathway to J. Substrate A is a feed-forward activator of the enzyme that catalyzes the synthesis of E. Products G and J are feedback inhibitors of the initial enzyme in the common pathway, and they also inhibit the first enzyme after the branch point in their own pathways. Draw a diagram showing the regulation of this metabolic pathway (3) Why is it advantageous for each of the two products to inhibit two enzymes in the pathway? (3) b) The Department of natural and applied sciences has developed two enzymes that degrade highly toxic compounds to non-toxic compounds. You have been tasked to degrade the greatest amount of the toxic compound in the shortest amount of time. The kinetic properties of the two enzymes are shown below: Enzyme Km Vmax A 12 mm 700mM/sec B 5 mm 400mM/sec At low concentrations of substrate which enzyme would be better to use based on the information given above? (Which enzyme binds the substrate better). Explain your answer. (3) At saturating concentrations of substrate, which enzyme would be better to use? (3) Explain your answer. QUESTION 5 [17] a) Write the deoxyoligonucleotide that will hybridize with a DNA containing the sequence (5')AGACTGGTC(3'). (2) b) C) Discuss the mode of action of small interfering RNAs (sirnas) (3) Discuss THREE (3) characteristics of the genetic code (6)

5 m Briefly discuss the following mutations: (6) Nonsense Mutation: Frame shift Mutation: Misense Mutation: QUESTION 6 [14] 3) Describe the following reactions: (6) Anabolic Reactions: Catabolic reactions: lll. Amphibolic reactions: b) Explain the Cori Cycle (4) c) Briefly discuss the regulation of the glycolysis pathway through the inhibition of Fructose 1,6-bisphosphatase by Adenosine Monophosphate (AMP). (4) QUESTION 7 [18] a) State the FOUR (4) enzyme sites that regulate gluconeogenesis (4) b) Oxidation of fatty acids generates large amounts of H20, which allows desert animals such as the camel and kangaroo rat to survive extended periods of time without taking a drink of water. localized to the inner mitochondrial What are the names of the two energy conversion processes membrane that use NADH, FADHz and ADP as substrates in reactions that result in the net production of H20? (2) With the aid of the fatty acyl CoA structure below, discuss the production of energy (ATP) through the process of B oxidation (breakdown) of fatty acids. (12) 0 CH3- (CH2); cnz- CH2-5- s Fatty acyi 00A - 00A THE END

Introduction to Carbohydrate metabolism

Introduction to Carbohydrate metabolism Some metabolic pathways of carbohydrates 1- Glycolysis 2- Krebs cycle 3- Glycogenesis 4- Glycogenolysis 5- Glyconeogenesis - Pentose Phosphate Pathway (PPP) - Curi