What is the Molecular Basis of Mutation?
Mutations are changes in the DNA sequence and can arise through various mechanisms. Spontaneous mutations occur naturally, often due to errors during DNA replication. Despite the proofreading, some errors escape, resulting in permanent mutations. Induced mutations result from external factors, or mutagens, such as:
- Chemical mutagens: Chemicals that modify DNA bases, leading to incorrect base pairing (e.g., base analogs, alkylating agents).
- Physical mutagens: Radiation (UV light, X-rays) causing DNA damage like thymine dimers or double-strand breaks.
- Biological mutagens: Viruses integrate their genetic material into the host genome.
Mutations can be point mutations, involving a single nucleotide change (substitutions, insertions, deletions). Substitutions can be silent (no change in protein), missense (different amino acids), or nonsense (premature stop codon). Insertions and deletions can cause frameshift mutations, altering the reading frame (Codons) of the gene.
Larger chromosomal mutations affect bigger DNA segments, including duplications, deletions, inversions, and translocations. These changes can impact protein structure and function, potentially leading to diseases or new traits. Understanding mutations is important for diagnosing genetic disorders, developing treatments, and studying evolution.
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