Concepts and formula to Remember
Key Points on Mutation
Definition and Importance
- Mutation: A permanent change in the DNA sequence, from a single base change to large chromosomal alterations.
- Impact: Causes protein sequence changes, affecting phenotype and providing genetic variation essential for evolution.
Mutation Based on Occurrence
Depurination:
- Loss of a purine base (adenine or guanine), potentially causing point mutations during replication.
Deamination:
- Removal of an amino group from a nucleotide (e.g., cytosine to uracil), possibly altering C-G to U-A base pairs.
Induced Mutation:
- Caused by environmental factors (UV light, radiation, chemicals).
Types of Induced Mutations
Base Analogs:
- Chemicals mimicking DNA bases; can lead to incorrect base pairing.
Base Modifying Agents:
- Add alkyl groups to bases, altering base pairing properties.
Intercalating Agents:
- Insert between DNA bases, causing frame-shift mutations (insertions or deletions).
Chromosomal Mutation
- Large-Scale Changes: Deletions, duplications, inversions, translocations, aneuploidy.
- Consequences: Potentially cause diseases, developmental issues, and evolutionary changes.
DNA Repair Systems
Direct Repair System:
- Reverses specific types of DNA damage (e.g., UV-induced thymine dimers).
Excision Repair System:
- Base Excision Repair (BER): Removes small base lesions, followed by DNA repair.
- Nucleotide Excision Repair (NER): Removes large DNA lesions, important for fixing UV damage.
BETA
