IV. How does E. coli regulate tryptophan synthesis? (10 points)

6. The figure below shows a newly transcribed mRNA still associated with the template DNA. Draw the stem-loop structure (with the sequence) that often forms during termination. (4 points)3'-GGTCGGGCGGATTACTCGCCCGAAAAAAAA-5'5'-CCAGCCCGCCUAAUGAGCGGGCUUUUUUUU-3'

7.Show the product of the following restriction digest. HindIII has a restriction site of A↓AGCTT. P- indicate the 5' phosphate, -OH indicates the 3' hydroxyl. (3 points)

8. A linear DNA molecule was treated with BamHI and gave two fragments with sizes of 2080 and 3600 base pairs. The same DNA was treated with EcoRI and gave three fragments of 1080, 2150 and 2450 base pairs. Finally, the DNA was treated with both enzymes at the same time and gave fragments of 1000, 1080, 1450 and 2150 base pairs. Provide a map of the DNA molecule clearly indicating the restriction sites. (4 points)

III. Explain and compare the following terms: (20 points)(1) Catabolite activator protein (CAP) and cAMP(2) Enhancer and silencer(3) Histone acetyItransferase and histone deacetylase(4) Nonsense-mediated decay and nonstop-mediated decay(5) Group I self-splicing and pre-mRNA splicesome

V. Explain the mechanism of RNA interference in eukaryotic cells. (10 points)

(1) What are the immediate-carly promoters after lambda infection? (2 points)

(2) Explain the functions ofN protein. (3 points)

(3) How does the lambda phage establish its lysogenic cycle? (5 points)

1. (12%) Compute xdx.

2. (12%) Find the area enclosed by the equation .