Difference Between Spontaneous and Induced Mutation

Spontaneous mutations arise naturally from internal cellular processes, while induced mutations result from external factors like chemicals, radiation, or biological agents. Both types of mutations can be beneficial, neutral, or harmful. Advancements in genome editing technologies, such as CRISPR-Cas9, hold promise for precise manipulation of genetic material, potentially reducing the occurrence of harmful mutations and enhancing beneficial ones.

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This Story also Contains

1. Mutation
2. Spontaneous Mutation
3. Induced Mutation
4. Difference between Spontaneous and Induced Mutation
5. Detection And Analysis Of Mutations

Mutation

A mutation is a change in the DNA sequence and affects genetic information carried by that sequence. They can result from errors during DNA replication, exposure to mutagens, or spontaneous chemical changes in DNA. Changes may range from small nucleotide changes to large changes in chromosomes.

Spontaneous Mutation

Spontaneous mutations are those that occur naturally, with no external influence. The former can be the result of random errors in DNA replication or from spontaneous chemical changes of DNA within the cell.

Causes

• Replication errors of the DNA

• Natural environmental factors; for example, radiation

• Spontaneous chemical changes of DNA. For example, the deamination of cytosine to uracil.

• Examples of spontaneous mutations in nature: point mutations in bacterial populations

Mechanism

• Misincorporation of nucleotides during DNA replication

• Tautomeric shifts, leading to mismatches in base pairing

• Spontaneous hydrolysis of the glycosidic bond in purine bases, that is depurination.

• Deamination: cytosine into uracil or adenine into hypoxanthine

Consequences

• Beneficial mutations: Offer advantages; e.g., antibiotic resistance in bacteria

• Neutral mutations: No effect is known on the fitness of an organism; they tend to be in non–coding regions

• Harmful mutation: Genetic disorders or a decrease in the fitness of the organism

Examples

• Beneficial: Lactose tolerance in humans

• Silent mutations in DNA

• Harmful: Sickle cell anaemia due to a single nucleotide change in the haemoglobin gene.

Induced Mutation

Induced mutations are those occurring as the result of exposure to external factors, called mutagens. It will be a chemical, physical or biological agent that alters the sequence of DNA.

Causes

• Chemical mutagens: Benzene, formaldehyde, ethidium bromide

• Physical mutagens: UV radiation, X-rays, gamma rays

• Biological agents: Certain viruses and bacteria that insert their genetic material into the host genome

• Examples of induced mutations in the laboratory, e.g. mutagenesis experiments in model organisms

Mechanism

• Chemical mutagens: can induce base modifications, insertions, deletions or cross-linking of DNA strands.

• Physical mutagens: can induce breaks of the DNA strands or thymine dimers

• Biological agents can introduce their genetic material, interfering with normal gene activity.

Consequences

• Beneficial mutations: Used in biotechnology and research, e.g. development of strains of bacteria for the production of certain compounds.

• Neutral mutations: These may not have any observable effect on the organism.

• Harmful mutations: Can be oncogenic or cause other kinds of genetic diseases.

Examples:

• Beneficial: Genetic engineering for herbicide resistance of crops

• Neutral: Those are induced but do not have negative effects on the protein's function

• Harmful: Induced by radiation and sometimes causing cancer.

Difference between Spontaneous and Induced Mutation

The table below depicts the key differences between Spontaneous and Induced Mutation:

Detection And Analysis Of Mutations

Techniques for Identifying Mutations:

• DNA sequencing: Determines the exact sequence of nucleotides in a DNA molecule, allowing for the identification of mutations

• PCR (Polymerase Chain Reaction): Amplifies specific DNA regions to detect and analyse mutations

• Gel electrophoresis: Separates DNA fragments based on size, allowing for the detection of mutations such as insertions or deletions.

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