Mutation.pptx https://www.youtube.com/@biologywithkiran5427

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Mutation is a change in the DNA sequence of an organism's genome. These changes can have various effects, ranging from benign to causing significant alterations in function or structure. Mutations can be classified based on their origin, effect, and the type of genetic material involved. Here are the main types of mutations:

Based on Origin
Spontaneous Mutations

Occur naturally and randomly, often during DNA replication or as a result of cellular processes.
Examples include replication errors and spontaneous chemical changes like deamination.
Induced Mutations

Result from exposure to external agents (mutagens) such as chemicals, radiation, or viruses.
Examples include UV radiation causing thymine dimers and chemical mutagens like benzene.
Based on Effect
Silent Mutations

Change in the DNA sequence that does not alter the amino acid sequence of the protein.
Often occurs in the third base of a codon due to the redundancy of the genetic code.
Missense Mutations

Change in the DNA sequence that results in the substitution of one amino acid for another in the protein.
Can affect protein function depending on the importance of the substituted amino acid.
Nonsense Mutations

Change in the DNA sequence that converts a codon into a stop codon, leading to premature termination of protein synthesis.
Usually results in a nonfunctional protein.
Frameshift Mutations

Insertion or deletion of nucleotides that are not in multiples of three, altering the reading frame of the gene.
Typically leads to significant changes in the amino acid sequence and often results in nonfunctional proteins.
Based on Type of Genetic Material
Point Mutations

Affect a single nucleotide pair.
Types include substitutions (transition and transversion).
Insertions and Deletions (Indels)

Addition or loss of one or more nucleotide pairs in the DNA sequence.
Can lead to frameshift mutations if the number of nucleotides inserted or deleted is not a multiple of three.

1. Mutation .

2. Mutation .

3. Introduction In DNA Mutants Mutagens

4. Based upon survival of individual

5. Based on tissue of Origin Somatic mutation Mutation in somatic cell Asexually reproducing individuals transmit them to next generations Germinal mutation Mutation in genetic cell Sexually reproducing individuals transmit them to next.

6. Based on cause of mutation Spontaneous mutation Naturally occurring Without any cause Rate is slow Rate in Eukaryotes> prokaryotes E.g : UV light in sunlight causes mutation in bacteria. Induced mutation Artificial Treatment with any physical & chemical agent. Mutagens E.g : X.RAY causing mutations in cereals.

7. Causes of Mutation DNA fails to copy accurately Naturally occurring linked to evolution E.g cell division, DNA replicates External influences Specific chemicals / agents Chemicals can generate mutation by De aminating amino groups Covalent modification Uv & X Ray radiations

8. Based on direction Forward mutation Normal wild type to mutant allele. Reverse mutation Mutant allele to normal wild type

9. Based on types of trait affected Visible mutation Affects phenotypic traits Visible Biochemical mutation Affects biochemical production Not visible

10. Other types Base Substitutions D eletions Insertions

11. Point mutation

12. Cont. Point mutations that occur in DNA sequences encoding proteins are either silent, missense or nonsense. Silent : If a base   substitution  occurs in the third position of the codon there is a good chance that a synonymous codon will be generated. Thus the amino acid sequence encoded by the gene is not changed and the mutation is said to be silent.

13. Missence : When base  substitution  results in the generation of a codon that specifies a different amino acid and hence leads to a different polypeptide sequence structure and properties of the substituted amino acid are very similar to the original amino acid the mutation is said to be conservative If the substitution leads to an amino acid with very different structure and properties the mutation is nonconservative   . Nonsense : When a base  substitution  results in a stop codon ultimately truncating translation and most likely leading to a nonfunctional protein

14. Deletion & Insertion a type of chromosomal aberration in which a segment of the chromosome is removed or lost . E.g Cystic fibrosis an  insertion  (also called an  insertion mutation ) is the addition of one or more nucleotide base pairs into a DNA sequence. This can often happen in microsatellite regions due to the DNA polymerase  slipping.

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