Comprehension Questions

* 1. What is the difference between somatic mutations and germ-line mutations?

* 2. What is the difference between a transition and a transversion? Which type of base substitution is usually more common? Why?

* 3. Briefly describe expanding trinucleotide repeats. How do they account for the phenomenon of anticipation?

4. What is the difference between a missense mutation and a nonsense mutation? A silent mutation and a neutral mutation?

5. Briefly describe two different ways that intragenic suppressors may reverse the effects of mutations.

* 6. How do intergenic suppressors work?

* 7. What is the difference between mutation frequency and mutation rate?

* 8. What is the cause of errors in DNA replication?

9. How do insertions and deletions arise?

*10. How do base analogs lead to mutations?

11. How do alkylating agents, nitrous acid, and hydroxylamine produce mutations?

12. What types of mutations are produced by ionizing and UV radiation?

*13. What is the SOS system and how does it lead to an increase in mutations?

14. What is the purpose of the Ames test? How are his~ bacteria used in this test?

*15. List at least three different types of DNA repair and briefly explain how each is carried out.

16. What features do mismatch repair, base-excision repair, and nucleotide-excision repair have in common?

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