Table of contents

1. Introduction to Genetics51m
2. Mendel's Laws of Inheritance3h 37m
3. Extensions to Mendelian Inheritance2h 41m
4. Genetic Mapping and Linkage2h 28m
5. Genetics of Bacteria and Viruses1h 21m
6. Chromosomal Variation1h 48m
7. DNA and Chromosome Structure56m
8. DNA Replication1h 10m
9. Mitosis and Meiosis1h 34m
10. Transcription1h 0m
11. Translation58m
12. Gene Regulation in Prokaryotes1h 19m
13. Gene Regulation in Eukaryotes44m
14. Genetic Control of Development44m
15. Genomes and Genomics1h 50m
16. Transposable Elements47m
17. Mutation, Repair, and Recombination1h 6m
18. Molecular Genetic Tools19m
- Genetic Cloning
  9m
- Methods for Analyzing DNA
  9m
19. Cancer Genetics29m
- Overview of Cancer
  21m
- Cancer Mutations
  7m
20. Quantitative Genetics1h 26m
21. Population Genetics50m
- Hardy Weinberg
  19m
- Allelic Frequency Changes
  31m
22. Evolutionary Genetics29m

17. Mutation, Repair, and Recombination

Induced Mutations

Genetics

17. Mutation, Repair, and Recombination

Induced Mutations

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1:47 minutes

Problem 5

Textbook Question

UV irradiation causes damage to bacterial DNA. What kind of damage is frequently caused and how does photolyase repair the damage?

Verified step by step guidance

span>UV irradiation frequently causes the formation of pyrimidine dimers, particularly thymine dimers, in bacterial DNA. These dimers result from covalent bonding between adjacent thymine bases on the same DNA strand, disrupting normal base pairing and DNA replication.

span>Photolyase is an enzyme that specifically recognizes and binds to these pyrimidine dimers in the DNA.

span>Once bound, photolyase absorbs light, typically in the blue or near-UV spectrum, which provides the energy needed for the repair process.

span>The absorbed light energy is used by photolyase to break the covalent bonds between the thymine bases, effectively reversing the dimerization and restoring the normal base pairing.

span>This repair mechanism is known as photoreactivation, and it is a direct reversal of the DNA damage caused by UV irradiation.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

UV-Induced DNA Damage

Ultraviolet (UV) irradiation can cause various types of damage to DNA, with the most common being the formation of pyrimidine dimers, particularly thymine dimers. These dimers occur when adjacent thymine bases bond together, disrupting the normal base pairing and leading to replication errors if not repaired.

Photolyase Enzyme

Photolyase is a light-dependent enzyme that repairs UV-induced DNA damage, specifically pyrimidine dimers. It utilizes energy from visible light to cleave the bonds between the dimerized bases, restoring the DNA to its original state and allowing normal replication and transcription to occur.

DNA Repair Mechanisms

DNA repair mechanisms are essential cellular processes that correct damage to DNA. In addition to photolyase, other repair systems like nucleotide excision repair (NER) and base excision repair (BER) exist, which recognize and remove damaged sections of DNA, followed by synthesis of new DNA to fill the gaps.