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 CELL BIOLOGY BIO-5005B 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 the Answer Grid or 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. Notes are not permitted in this examination. Do not turn over until you are told to do so by the Invigilator. BIO-5005B Module Contact: Dr Jelena Gavrilovic, BIO Copyright of the University of East Anglia Version 1

2 2 SECTION A: MULTIPLE CHOICE AND SHORT ANSWER QUESTIONS Answer ALL questions [40 marks] Answer multiple choice questions in the answer grid provided and attach this to your booklet for Section A. Unless stated otherwise, all multiple choice questions have ONE answer. 1. Which of the following does not apply to SH2 domains? [1 mark] a) They are conserved domains first identified in Src b) They play an essential role in some receptor signal complexes c) They bind to proline rich sequences in erk/map kinase d) They contain a pocket that binds to phosphorylated tyrosine e) They are involved in the MAP kinase pathway 2. During which stage of the Cell Cycle does DNA synthesis occur? [1 mark] a) G0 phase b) M phase c) G1 phase d) G2 Phase e) S phase 3. Which of these extracellular hormone types bind to intracellular receptors? [1 mark] a) Nucleotides b) Proteoglycans c) Polypeptides d) Steroids e) ATP 4. T cell surface receptors for antigen partly recognise: [1 mark] a) cytokines b) MHC c) antibody d) IL-2 e) chemokines Section A continues on next page/...

3 3 Section A continued The prime role of Cyclin proteins is to promote cell: [1 mark] a) migration b) metastasis c) division d) differentiation e) death 6. Binding of a hormone to a receptor tyrosine kinase causes all of the following except: [1 mark] a) dimerization of the receptor b) autophosphorylation of the receptor c) activation of Ras through an interaction with GRB2 and Sos d) hydrolysis of GTP bound to Ras e) changes in gene expression 7. Microtubule dynamic instability is associated with: [1 mark] a) GTP hydrolysis b) ATP hydrolysis c) ARP2/3 activation d) phosphorylation/dephosphorylation cycles e) Activation of cofilin 8. Keratin is a type of: [1 mark] a) motor protein b) nuclear protein c) actin cross linker d) intermediate filament protein e) membrane protein 9. Microtubules are nucleated by: [1 mark] a) ARP2/3 complex b) formins c) TuRC d) cofilin e) kinesin Section A continues on next page/... TURN OVER

4 4 Section A continued Which of the following is involved in actin filament nucleation? [1 mark] a) Gamma-tubulin b) plectin c) Arp2/3 d) kinesin e) cofilin 11. What does the term hyperplasia mean? [1 mark] a) Increase in cell size b) Increase in cell number c) Increase in cell migration d) Increase in cell secretion e) Increase in cell width 12. The clathrin triskelion is formed from which of the below? [1 mark] a) 3 lights chains and 3 heavy chains b) 2 lights chains and 2 heavy chains c) 2 lights chains and 3 heavy chains d) 1 heavy chain subunit e) 3 light chain subunits 13. EGF binds to cells through which type of cell surface receptors? [1 mark] a) Integrins b) Receptor Tyrosine kinases c) G-protein coupled receptors d) Steroid receptors e) Hormone receptors 14. Which one of the following phenotypic and biochemical changes is specifically observed in apoptotic cells? [1 mark] a) Swelling of nucleus b) Phosphatidylserine is concentrated on the inner layer of plasma membranes c) Massive release of cytoplasmic proteins to the surrounding medium/tissue d) Substantial increase of cell volume (Swelling) e) Increased amounts of small DNA fragments Section A continues on next page/...

5 5 Section A continued Staining of cells with propidium jodide (PI: fluorescent DNA-specific marker) and fluorescence labelled annexin V (binding to phosphatidylserine) is used to identify vital, apoptotic or dead cells by flow cytometry. Which staining pattern is typically seen in apoptotic cells when compared with vital cells? [2 marks] a) No staining with both markers b) Positive staining with PI, but no binding of labelled annexin V c) No (or weak) staining with PI, but significant binding of labelled annexin V d) Strong staining with PI but no binding of labelled annexin V e) Strong PI staining exclusively in released membrane vesicles 16. Which of the following biochemical events directly induces strong immune reactions as a consequence of cell death by necrosis, but not by apoptosis? [1 mark] a) Release of nuclear proteins into the extracellular space b) Degradation of genomic DNA results in randomly sized fragments c) Release of apoptotic vesicles d) Excessive activation of effector caspases e) Altered distribution of membrane lipids changing membrane polarity 17. Which analytical method would be most useful to detect individual apoptotic epithelial cells in tissue sections of human skin? [1 mark] a) Detection of apoptosis-specific DNA fragments by gel electrophoresis b) Distinction of active and inactive caspases by immunoblotting c) Staining with fluorescently labelled annexin V for detection of changes in membrane polarity d) Use of propidium jodide for the detection of cytoplasmic RNA e) Detection of caspase-generated fragments of keratins by using specific antibodies recognizing neo-epitopes of keratins 18. Monocytes attach to ICAM1 on activated endothelial cells through which receptors? [1 mark] a) Beta 2 integrins b) Beta 1 integrins c) Receptor Tyrosine Kinases d) Selectins e) Nuclear hormone receptors Section A continues on next page/... TURN OVER

6 6 Section A continued In which location are collagens not found? [1 mark] a) Skin b) Bone c) Basal lamina d) Blood e) Connective tissue stroma For all remaining questions in Section A, please use an answer booklet. Remember to attach your multiple choice answer grid to the booklet. 20. Briefly describe the molecular mechanisms underpinning LAD-1 (Leukocyte Adhesion Deficiency-1) and the consequences to the patient. [5 marks] 21. Briefly describe induced pluripotency and how this can be achieved at the molecular level. [4 marks] 22. Describe the biochemical principle of the TUNEL method (=TdT-mediated dutp Nick End Labeling) for the detection of apoptotic cells. [5 marks] 23. Name two Medical and/or Research uses for antibodies. [2 marks] 24. What is the centrosome composed of and what is its main function? [4 marks] END OF SECTION A START YOUR ANSWER TO THE NEXT SECTION IN A NEW BOOKLET Section B begins on next page/...

7 7 SECTION B: DATA HANDLING QUESTION ANSWER THIS SECTION IN A NEW BOOKLET Answer ALL PARTS of this question [30 marks] 25. Read through the background information before you start to answer this question. Background Information Epithelial cells undergo EMT (epithelial mesenchymal transition) in a number of situations including tumour invasion when the cells start to migrate. In order to explore the role of Epidermal Growth Factor (EGF) in EMT in a new epithelial cell line, EGF has been added to individual cell culture wells containing the cells and observations made over time. At the days indicated cell extracts were made and western blots for keratin and vimentin were performed. The data obtained is shown in Figure 1 below. Keratin Vimentin Figure 1. Western blot analysis from an epithelial cell line treated with EGF on Day 0. Cell extracts were isolated from the epithelial cells on the indicated day and a Western blot performed for (A) keratin and (B) vimentin. The protein band in each Western blot lane was scanned to obtain protein content and this data was plotted in the graphs under each Western blot. Section B Q25 continues on next page/... TURN OVER

8 8 Section B Q25 continued... (a) Describe the data shown in Figure 1 (A) and (B), commenting on the fold-change over time. [7 marks] (b) Explain briefly how this Western blot of cell extracts was likely to have been performed. [8 marks] (c) How could the western blot experiment be improved? [4 marks] (d) During the experiment you observe the cells under a microscope on each day. What changes in cell morphology and cell-cell interactions would you expect to see? Use a diagram to illustrate your answer. How could you confirm your observations that the cells are undergoing EMT? [5 marks] (e) Design a new experiment with the same epithelial cells to explore the role of EGF signalling in a cell migration assay. [6 marks] END OF SECTION B START YOUR ANSWER TO THE NEXT SECTION IN A NEW BOOKLET Section C begins on next page/...

9 9 SECTION C: ESSAY QUESTION ANSWER THIS SECTION IN A NEW BOOKLET Answer ONE question [30 marks] 26. What are intermediate filaments and why are they not polar, like microtubules and actin filaments? 27. Why can t damaged axons regenerate in the central nervous system, when they can in the peripheral nervous system? Answer this question by briefly describing the intermediate steps of peripheral nerve regeneration and then considering factor/s that inhibit and limit the regeneration of axons in the central nervous system. 28. Answer BOTH parts (a) and (b). Phagocytosis is an essential process to eliminate apoptotic and dead cells from tissues. (a) How can phagocytes distinguish dead cells from vital normal cells? [15 marks] (b) What happens after the recognition of dead cells by phagocytes? [15 marks] END OF PAPER

10 UNIVERSITY OF EAST ANGLIA School of Biological Sciences Main Series UG Examination CELL BIOLOGY BIO-5005B Registration Number SECTION A: Answer Grid (for Multiple Choice Questions only) Place a single cross in the appropriate box Question No. A B C D E Marks given Marks available