Principles of Molecular Biology – I — DU B. Sc. (Hons) Microbiology Previous Year Question Papers

I. Define the following (any nine) : ' 9×2=18 (iv) Transcription unit (viti) Hyperchromicity (ix) Writhe of DNA (x) Linker DNA. 2. (a) Differentiate between the following (any three) : 3×5=15 (i) Topoisomerase I and II (b) Write the functions of the following (any three) : 1×3=3 (io) Sliding clamp. (a) Write short notes on the following (any three) : 3×5=15 (ii) General transcription factors in eukaryotes (iii) Structure and function of tRNA (io) Termination of transcription in prokaryotes. (6) What are the mechanisms of regulating DNÁ replication in prokaryotes? 3 4. (a) Why is the fidelity of DNA replication important, and how is it maintained? 6 (b) Write the significance of cot curves. Discuss the method of cot curve analysis of DNA. 6 (c) Briefly explain the importance of enhancers and silencers in gene regulation. 6 (a) Describe the events that occur at the origin of replication during the initiation of DNA replication in Saccharomyces cerevisiae cells. 6 (6) What is the linking number ? Calculate the linking number of a covalently closed circular DNA with 5880 base pairs having 10 negative supercoils. 4 (c) What do you understand by the promoter strength? What are the factors that determine promoter strength ? 4 (d) Write the mode of action of any one inhibitor each of prokaryotic and eukaryotic transcription. 4 6. (a) Discuss any two modes of replication of circular DNA. 6 (b) Describe the contribution of the following scientists (any three) : 6 (ii) Arthur Kornberg (iii) John Cairns (io) Thomas Cech. (c) What is telomerase ? Write its significance and diagrammatically explain its mechanism of action. 6