1. MUTATION Dr.H.B.Mahesha Associate Professor and Head
Department of Sericulture
Yuvaraja’s College
University of Mysore, India.
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2. Significance of Mutations
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3. The organism which undergoes mutation is known as mutant
Mutation is an abrupt qualitative or quantitative change in the genetic material/
Any change in the nucleotide sequence of DNA, which gives rise to a mutant genotype
The organism which undergoes mutation is known as mutant
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4. History
Seth Wright, 1791
Mutation - Coined by Hugo de Vris in1900 to explain the heritable changes in evening primrose Oenothera lamrckiana
Mutagenesis - Process of producing mutations
Mutagen - A physical/chemical/biological agent that causes mutations
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5. T.H.Morgan T.H. Morgan 1910 Drosophila melanogaster
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6. Classification
Based on the origin: Natural / Artificial (induced) Based on the cells: Somatic/Gametic Based on chromosomes: Autosomal / Allosomal Based on direction: Forward/Reverse Based on size: Point/Gross Silent Mutations. Leaky mutations. Nonsense Mutations or Chain termination Mutation etc.,
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7. Natural Mutation Frequency of total mutations - 10-7 to 10-12/organism
(i.e., )
Frequency of detectable mutations – 1 in 106 (i.e., )
Eg., Tautomerism:-The ability of a molecule to exist in more than one chemical form
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8. Tautomerism
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9. Induced Mutation
Induced artificially by exposing them (organisms) to abnormal environment.
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10. Mutagens Physical –Radiations: i. Ionizing-X-rays, gamma, Alpha,
Beeta, protons, nutrons etc.,
ii. Non Ionizing -UV
Temperature-
Chemical – Auerbach & Robson 1947
Base Analogues: 2,aminopurine, 5-bromourasil etc.,
Base Modifying agents: Nitrous acid, Hydroxylamine etc.,
Distortion producing agents: Proflavin, acridine orange etc.,
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11. Biological Mutagens: H. Pylori Hepatitis virus H. papiloma virus
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12. Point Mutation / Gene Mutation
A mutation that changes only one small area or one nucleotide in a gene Earliest record of point mutation dates back to 1791 by Seth Wright. Since then mutations have been reported in E. coli, Neurospora, Pea, Maize, Rodents, Fowls, Man, etc.,
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13. Frame Shift Mutation
A mutation that inserts or deletes a single base (normally single rarely more) will change the reading frame for the entire subsequent sequence. A change of reading frame is called Frame shift mutation.
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15. Frame Shift Mutation may be Deletion Insertion
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16. Substitution:- 1. Transition 2. Transversion
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17. Transversion
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18. Chemical Mutagenesis Morgan 1934 – Drosophila with Alcohol
Chemicals: Activity can not be guessed based on
structure
Types:
Copy Errors by Base Analogues
Direct Effect on DNA
Agents Producing Distorsions in DNA
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19. Copy Errors by Base Analogues
Eg.,
Thymine Bromouracil
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20. Sunday, 11 November 2018

21. Guanine  Uracil =Adenine
Direct Effect on DNA eg., Nitrous acid (HNO2), Hydroxylamine (NH2OH),Alkylating agents
Guanine  Uracil =Adenine
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22. Cytocin (NH2OH)  Modified Base=Adenine
Alkylating Agents: EMS, EES, DES, etc., are extensively used in genetic research.
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23. Agents Producing Distortions in DNA
Eg., Acridine Orange & Proflavin
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24. 
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25. Intercalation resulting in addition of the base
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26. Intercalation resulting in deletion of the base
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27. RADIATION MUTAGENESIS
Ionizing radiations:- High-energy radiation capable of producing ionization in substances through which it passes.
Ionization:- Any process that leads to the dissociation of a neutral atom, molecule or other species into ions; the state of being ionized.
Eg., X-rays, α, β, gamma rays, fast moving particles etc.,
Non Ionizing radiations:- Uv, Radio waves,
Visible Light
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28. Effect of radiation on DNA molecule
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29. Thymine Dimers T=T  50% T=C  40% C=C 10% Sunday, 11 November 2018

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31. Ionizing
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32. Acknowledgements to INTERNET FOR PICTURES
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