1. DNA may be repaired by removing a mutation and replacing it, so-called excisi

Question

1. DNA may be repaired by removing a mutation and replacing it, so-called excision repair. Which mutation can actualliy be repaired directly by a A. pyrimidine dimers B. mismatched bases C. methylation of bases, such as 1-methylguanine or 3-methycytosine D. uracil incorporated into DNA requiring light? r bond formation? 2. What do MOST bacterial DNA ligases use for A. GTP B. ATP C. TTP D. CTP E. NAD 3. Signal transduction systems incorporate molecules that have other cellular functions. What second messenger molecule plays a role in activating bacterial gene transcription? A. cGMP B. inositol 145-trisphosphate C. 1.2-diacylglycerol D. calcium E. cAMP 4. What is removed from the RNA primary transcript in order to produce mRNA? A. TATA boxes B. recombination signal sequences C. introns D. promoter sites E. polyadenylation 5. What is a 5' cap, structurally? A. 7-methylguanosine on the 5' end of RNA B. a sequence of adenosine residues added to the 5' end of the RNA C. 3-methyluracil added to the 5' end of the RNA D. 5-methylguanosine on the 3' end of the RNA E. methylation of the 5' base of RNA, preventing further addition of bases

Explanation / Answer

1 answer A. UV irradiation induces pyrimidine dimer formation in the DNA. Photoreactivation is a DNA repair mechanism that removes pyrimidine dimers, using light energy.

2. All bacterial DNA ligases are NAD+ dependent

4. Intron sequences are removed from the primary RNA transcript

5. Answer A 7 methyl guanosine which is dded to 5' end of mRNA to protect it from degradation

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