Q1. Prokaryotic cell E. coli consists of a single closed-circular DNA molecule of 4.6 x 106 bp long. This DNA molecule would be 1.6 mm if the double helix is relaxed. Please describe what strategies does E. coli use to pack such a long molecules into its nucleoid less than a micrometer (mm) in diameter. (20 points)
1. What are the gene expression stages that can be regulated? (10 points) Regulated stages in gene expression: (1) transcription initiation (the most important stage): RNAP binding of the promoter, transition from the closed complex to the open complex; promoter escape 4’ (2) stages after initiation (elongation and termination) 2’ (3) RNA processing (alternative splicing) in eukaryotes 2’ (4) translation 2’
Your answer should describe what each item is and how it functions in the cell. Diagrams, structure and sequence information could be included in your answer, as necessary. 1. Affinity chromotography 2. microRNA 3. Alternative splicing 4. Insulator 5. Riboswitch 6. Wobble concept 7. Topoisomerase
