Introduction
Mutation is a change in the DNA sequence of an organism.
Can occur spontaneously during DNA replication or be induced by external factors like radiation, chemicals, or viruses.
May result in altered genetic information that is inherited by offspring.
Can produce beneficial, neutral, or harmful effects on the organism.
Types of Mutations
Point Mutation – A single nucleotide base pair is altered.
Insertion or Deletion Mutation – One or more nucleotide base pairs are added or removed, potentially causing frameshift mutations.
Chromosomal Mutation – Structural or numerical changes in chromosomes, such as translocations, inversions, or duplications.
Spontaneous Mutation – Naturally occurring mutations without external influence.
Induced Mutation – Caused by external mutagens like radiation, chemicals, or viruses.
Duplication – Extra copy of a DNA segment, which can affect gene function.
Inversion – Reversal of a DNA segment, potentially leading to genetic disorders.
Types of Mutagens
A) Chemical Mutagens
Alkylating Agents – Add alkyl groups to DNA, causing mispairing (e.g., EMS, MMS).
Base Analogs – Mimic nucleotides, leading to errors in replication (e.g., 5-bromouracil, 2-aminopurine).
Intercalating Agents – Insert between base pairs, causing frameshift mutations (e.g., ethidium bromide, proflavine).
Reactive Oxygen Species (ROS) – By-products of metabolism that damage DNA.
B) Physical Mutagens
Ionizing Radiation – X-rays, gamma rays, and cosmic rays cause DNA strand breaks and chromosomal abnormalities.
Ultraviolet (UV) Radiation – Causes pyrimidine dimer formation, interfering with DNA replication.
High Temperature – Can denature DNA, leading to strand breaks.
Effects of Mutation
Neutral Effect – No impact if it occurs in non-coding regions or results in silent mutations.
Harmful Effect – Can lead to genetic disorders like cystic fibrosis or cancer by disrupting protein function.
Beneficial Effect – In rare cases, can enhance survival (e.g., antibiotic resistance in bacteria).
Conditional Effect – Impact depends on environmental factors (e.g., temperature-sensitive mutations).
Lethal Effect – Mutations affecting essential genes may cause embryonic lethality.
