二、FILL IN: （20 points, 1point for each) 1. Any pi...

二、FILL IN: (20 points, 1point for each) 1. Any piece of DNA which replicates as a single unit is called a (). 2. Almost all RNA start sites consist of a () residue. G is more common at the transcription start site than A. 3. RNA Pol III synthesizes the precurssors of () rRNA, tRNA and other () and cytosolic RNAs. Like RNA Pol II, it is located in the (). 4. The tRNA () adds the sequence 5’-CCA-3’ to the 3’-end to generate the mature 3’-end of the tRNA in tRNATyr processing of eukaryotes. 5. The replicase in prokaryotes is (), while in eukaryotes is (). 6. The major force involved in maintaining the secondary structure of protein is () bond. 7. In NER，an endonuclease () cleaves the DNA a precise number of bases on either side of the lesion. In E.coli, the gap is filled by () and the final phosphodiester bond made by (). 8. Enzymes exist which regulate the level of supercoiling of DNA molecules, these termed (). 9. The () factor is not required for transcription elongation and is released from the transcription complex after initiation. The remaining enzyme, which translocates along the DNA, is known as the () enzyme. 10. The assembled ribosome has two tRNA-binding sites. These are called the A- and P-sites, for () and () sites. 11. Alternative splicing includes the following items: alternative selection of (), alternative selection of poly(A), retention of an () and () skipping.