Time allowed: 2 hours Answer ALL questions in Section A, ALL PARTS of the question in Section B and ONE question from Section C.

Transcription

1 UNIVERSITY OF EAST ANGLIA School of Biological Sciences Main Series UG Examination FUNDAMENTALS OF CELL BIOLOGY AND BIOCHEMISTRY BIO1A14 Time allowed: 2 hours Answer ALL questions in Section A, ALL PARTS of the question in Section B and ONE question from Section C. Write answers to EACH SECTION in a SEPARATE booklet. The maximum number of marks available for your answers in SECTION A is 40 marks The maximum number of marks available for your answer in SECTION B is 30 marks The maximum number of marks available for your answer in SECTION C is 30 marks The TOTAL number of marks available for the paper is 100 Numbers in square brackets [ ] indicate the relevant mark applied to each part of the question. Graph paper is provided. Notes are not permitted in this examination. Do not turn over until you are told to do so by the Invigilator. BIO1A14 Module Contact: Dr Helen James, BIO Copyright of the University of East Anglia Version 1

2 2 SECTION A Answer ALL questions. Unless stated otherwise all multiple choice questions have ONE answer. 1. What is meant by the terms tertiary and quaternary when discussing the structure of proteins? [2 marks] 2. Myosin is composed of which of the following combinations of peptides? a) Two heavy chains plus four light chains b) Two heavy chains plus two light chains c) Four heavy chains plus two light chains d) Four heavy chains plus four light chains e) One heavy chain and one light chain 3. What units are associated with the specific activity of an enzyme? 4. Which metal ion is located in the active site of carbonic anhydrase? a) Nickel b) Iron c) Copper d) Zinc e) Magnesium 5. In anion exchange chromatography what is the charge of the matrix; positive, negative or no charge? 6. The phylogenetic classification of the three domains of life was established based on the sequences of what? a) Ribosomes b) 16S ribosomal RNA c) 24S ribosomal RNA d) 30S ribosomal subunit e) 50S ribosomal subunit 7. Briefly, how do the processes of transcription and translation differ when comparing bacteria to eukoryotes? [3 marks] Section A continues/...

3 3.. /Section A continued 8. What are the three main cytoskeletal filaments? [3 marks] 9. What is immunofluorescent labelling used for? [2 marks] 10. Name a cellcell adhesion complex which is never connected with the cytoskeleton. Briefly define its organisation and major component. [3 marks] 11. Which of the following chemical features is never found in typical collagen proteins? a) Formation of a triple helix b) Heparin c) 3Hydroxyproline d) Primary sequence contains repetitions of (GlyXY) e) Glycosylation 12. Briefly describe the function of the RGDmotif in extracellular matrix proteins. [4 marks] 13. Where in the cell do membrane proteins become glycosylated, and which amino acid can become Nlinked to glycosyl groups? [2 marks] 14. What are the 3 distinct stages of interphase in the eukaryotic cell cycle, and during which phase does DNA replication occur? [4 marks] 15. Which of the following is not a 2nd messenger? a) Cyclic AMP b) Cyclic GMP c) Diacylglycerol d) Inositol trisphosphate (IP3) e) Zinc ions Section A continues/... TURN OVER

4 4... /Section A continued 16. The longitudinal files of cells in the root system of flowering plants are generated as a result of which plane of cell division? a) Periclinal b) Parallel c) Asymmetric d) Anticlinal e) Mesoclinal 17. Which of the following genes is required for specifying the endodermal cell layer of the root system? a) Shortroot b) Longroot c) Beetroot d) Fatroot e) Trunkroot 18. The energy released during glycolysis and citric acid cycle is transferred to the enzymes of oxidative phosphorylation by which two molecules? [2 marks] 19. What name is given to all monosaccharides that contain five carbons in their backbone? 20. Two molecules A and B are shown below. Which is a ketose? A B Section A continues/...

5 5... /Section A continued 21. An enzyme used in both glycolysis and gluconeogenesis is: a) 3phosphoglycerate kinase b) Glucose 6phosphatase c) Hexokinase d) Phosphofructokinase1 e) Pyruvate kinase 22. Generally, hormones that are peptides act faster than those that are steroids. Briefly explain why this is true. [3 marks] END OF SECTION A Section B begins on next page... TURN OVER

6 6 SECTION B Answer ALL PARTS of the question 23. (a) Cisaconitate has an extinction coefficient of 3500 M 1 cm 1 at 240 nm. What is the concentration (M) of cisaconitate in a solution that that gives an absorbance of 0.37 at 240 nm in a 1 cm path length cuvette? Assume that cisaconitate is the only molecule in the cuvette that absorbs at 240 nm. [6 marks] (b) Aconitase is an enzyme that obeys MichaelisMenten kinetics for the formation of isocitrate from cisaconitate as described by the equation below. CH 2 CH 2 C C + H 2 O H HO C C H H cisaconitate isocitrate Table 1 below shows the initial rate of isocitrate formation in a series of assays where the only difference was the initial concentration of cisaconitate. cisaconitate concentration (M) 2 x x x 10 5 initial rate (M s 1 ) 8.3 x x x 10 8 Table 1. Initial rate of isocitrate formation (i) Determine the Michaelis constant, K M, and the maximum velocity, V max, from the results above using a graphical analysis. [15 marks] (ii) The results presented above were obtained from solutions of 2 ml final volume that contained 5 µl of a stock aconitase solution. The stock aconitase solution was 10 µm. What was the concentration of aconitase in the assay? [6 marks] (iii) Calculate the turnover number, k cat, of the aconitase. [3 marks] END OF SECTION B Section C begins on next page...

7 7 SECTION C Answer ONE question 24. Describe the fundamental principles of how hormonal cascades result in large amplification of the original signal. More specifically, for glucose homeostasis highlight the metabolic pathways that are affected by glucagon and insulin, contrasting how these hormones influence metabolism. [30 marks] 25. Answer BOTH parts (a) and (b): (a) Eukaryotic and prokaryotic cells are bound by cell membranes that share common features. What are the key molecules that constitute a membrane and how do these contribute to the membranes functions? [20 marks] (b) In addition to the membrane, prokaryotic cells and some eukaryotic cells have cell walls. Compare and contrast the different types of cell walls. [10 marks] 26. With reference to the initiation of flowering in Arabidopsis thaliana, describe how plant cells communicate over short and long distances. [30 marks] END OF PAPER

8 8 BIO1A14 EXAMINATION MARKERS Question No. 1 st Marker 2 nd Marker Section A Q122 Dr H James Dr K Yeoman Section B Q23 Prof J Butt Dr H James Section C Q24 Dr R Bowater Dr H James Section C Q25 Dr H James Dr G Kelemen Section C Q26 Dr C Thomas Dr H James