武汉大学生命科学学院：《分子生物学》（英文版）2005Quiz1

(4 points each) 1. Cre recombinase ng-ty 6. 30-nm fibe 7. Core histones 8. Origins of replication 9. Phosphoester bond 10. Nucleoside Answer the following questions(15 points each, select 4 questions) 1. Explain why the replication machinery is incapable of completely replicating the ends of the chromosomes. What would be the consequence if the ends were not completely replicated? How do eukaryotic cells get around this problem? 2. If an organism is exposed to UV light, what kind of DNA lesion will likely be resulted? What are the mechanisms that may repair such a lesion? 3. Describe the roles of the proteins involving in the RecBCD pathway, a major DSB-repair pathway 4. How do viral-like retrotransposons and retrovirus move them around the host genome? Compare the mechanism with the cut-and-paste mechanism of DNA transposition Extra questions (10 points each) 5. How eukaryotic chromosomes are ensured to be replicated exactly once per cell cycle? 6. Describe the"trombone"model for coordinating replication by two dNa polymerases at the e. li. replication fork. 7. Briefly summarize the palm, thumb, and finger domains of DNA polymerase, and explain how they contribute to replication. What is the role of the metal ions in the palms activity?

Describing the following terms (4 points each) 1. Cre recombinase 2. CSSR recombination 3. Mating-type switching 4. Mismatch repair 5. Polymerase switching 6. 30-nm fiber 7. Core histones 8. Origins of replication 9. Phosphoester bond 10. Nucleoside Answer the following questions (15 points each, select 4 questions) 1. Explain why the replication machinery is incapable of completely replicating the ends of the chromosomes. What would be the consequence if the ends were not completely replicated? How do eukaryotic cells get around this problem? 2. If an organism is exposed to UV light, what kind of DNA lesion will likely be resulted? What are the mechanisms that may repair such a lesion? 3. Describe the roles of the proteins involving in the RecBCD pathway, a major DSB-repair pathway in E. coli. 4. How do viral-like retrotransposons and retrovirus move them around the host genome? Compare the mechanism with the cut-and-paste mechanism of DNA transposition Extra questions (10 points each) 5. How eukaryotic chromosomes are ensured to be replicated exactly once per cell cycle? 6. Describe the “trombone” model for coordinating replication by two DNA polymerases at the E. coli. replication fork. 7. Briefly summarize the palm, thumb, and finger domains of DNA polymerase, and explain how they contribute to replication. What is the role of the metal ions in the palm's activity?