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DNA Mutation and Repair Pathways in Genetics

Explore the concepts of DNA mutation, repair mechanisms, and genetic phrases in this informative chapter. Understand the stability of DNA duplexes and the various repair pathways involved in maintaining genetic integrity.

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DNA Mutation and Repair Pathways in Genetics

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  1. Chapter 16 Mutation, Repair and Recombination

  2. Question • Lysine and arginine are two amino acids with similar sized “R” (side-) groups and similar biochemical behavior (for example, both are basic residues). A mutation results in substitution of lysine for arginine and has no detectable effect on the function of that protein. Which statement best applies to this situation? • The mutation is a silent mutation. • The mutation is a frameshift mutation. • The amino acid change is conservative. • The amino acid change is silent. • This organism displays no codon bias.

  3. Question • Which of the following represents a correct or acceptable phrase in genetics? • Mutant protein • Protein mutation • DNA mutation • A and C • All of the above

  4. Question • Which of the following statements is correct about the bases in DNA under normal circumstances: • Adenine should pair with thymine. • The bonds holding guanine and cytosine together are stronger than the bonds holding adenine and thymine together. • A purine always binds to a pyrimidine. • A substitution of adenine for guanine is a transition mutation. • All of the above

  5. Carcinogens and the Ames Test

  6. Repair mechanisms • Photo reactivation repair • Base excision repair • Nucleotide excision repair • Transcription coupled repair • Mismatch repair

  7. Undamaged DNA UV light (mutagenic agent) EMS, NG (mutagenicagent) Pyrimidine dimers Methylated base Visible light Inactivated after action Alkyl Transferase Photolyase Original Base

  8. Replication dependent repair

  9. Question • Which of the following repair pathways do not involve the use of a homology-dependent repair system? • Base excision repair • Photo reactivation repair • Transcription coupled repair • Nucleotide excision repair • Mismatch repair

  10. Question • Which of the following DNA duplexes is most stable? • 5’AATTAATTAATTAATTAATT 3’ • 3’TTAATTAATTAATTAATTAA 5’ • 5’ GGCCGGCCGGCCGGCCGGCC 3’ • 3’ CCGGCCGGCCGGCCGGCCGG 5’ • Both are equally stable. • B is more stable than A.

  11. Question • Which of the following repair pathways do not involve the use of a homology-dependent repair system? • Base excision repair • Photo reactivation repair • Transcription coupled repair • Nucleotide excision repair • Mismatch repair

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