Molecular Biology — DU B. Sc. (Hons) Biomedical Previous Year Question Papers

(v) Shine Dalgarno sequence (b) What is RNA editing. Explain its significance. 5 5. (a) CAiny Schematic representation of the fo4xyit2 (Any 4) (i) Transcription initiation in Prokaryotes (ii) tRNA clover leaf structure (iii) Rolling circle model of replication (vi) Steps in 5' Capping of mRNA human cells. ! (b) Explain how steric hinderance can lead to mutually exclusive splicing. (d) How do stop codons terminate translation? Explain the role of release factors (e) subpare of the questions should be attempted (a) reye illustrations and examples wherever 1. (a) Define: (Any 5) 5x2=10 (i) Semi-conservative mode of replication (ii) Core promoter (iv) Transition mutation (v) Ribosome cycle (vi) Exon shuffling (vii) Promoter escape (b) Give one word for the following: (Any 1°10x2-20 The initiator tRNA is coupled to this amino acid (ii) Group of factors required for efficient and In enterspecific initiation of transcription (iii) The protein responsible for both RNA Polymerase removal and recruitment of repair machinery during transcription (iv) A sequence that is generally conserved across species and is required for a particular function (V) A repair pathway that potentially introduces mutations vi) E. coli enzyme that methylates A residues in both strands of the sequence 5'- GATC-3 (vii) Repair system correcting replication errors (ix) Structural problem caused by unwinding ahead of replication fork (x) Ability of RNA polymerase to start synthesis without primer (xi) Simultaneous translation by multiple ribosomes (xii) Enzyme ensuring correct amino acid-tRNA pairing 2. (a) Jai by the following statements as true of x2-10 (i) Eukaryotic DNA is replicated exactly once per cell cycle. i) Translation initiation factors hold eukaryotic mRNAs in circles. (iii) Steps in eukaryotic transcription are regulated by phosphorylation of CTD tail of (vi) Okazaki fragments are synthesized continuously and later broken into smaller pieces. (V) Stop codons encode special amino acids that terminate translation. (vi) Both strands of DNA are transcribed equally for a given gene. (b) Discuss the molecular basis of UV-induced DNA damage and the mechanisms used by cells to repair it. 5 3. Differentiate between the following: (Any 3) ( Prodependent Vs Rho independent transcription. (ii) Group I Vs Group II self-splicing introns 4. (a) Give the Role/Significance of the following: (Any 5) (i) Fail safe glycosylases (vi) Base analogs