Mutation: Definition, Types, Application

Mutation: Definition, Types, Application

Introduction:-

The Replication And Distribution Of Genetic Material Are Extremely Precise So That The Genetic Information Is Usually Passed On From One Generation To The Next Without Alteration. But Occasional Errors Do Occur Both During Replication And Distribution Of The Genetic Material Giving Rise To Sudden Heritable Changes In The Characters Of Organisms, Such Alterations Are Called Mutation, While Individual Showing These Changes Are Known As Mutants.

Definition:-

Sudden Genetic Changes In Any Type Of Organism That Called Mutation.

MUTATION:-

Sudden, heritable changes in genetic material are called mutation.

MUTAGENESIS: –

The mutant organism formation process is known as mutagenesis.

HISTORICAL

The Term “Mutation” Was Introduced By Hugo De Vries In 1900. Systematic Studies On Mutation Began In 1910 With The Discovery And Genetic Analysis Of The White Eye Mutant Of Drosophila By Morgan.The Discovery By H.J. Muller Of Mutagenic Action Of X-Rays In 1927 In Drosophila.

CHARACTERISTICS OF MUTATION

  • There Seems To Be No Difference In The Nature Of Spontaneous And Induced Mutations.
  • Most Mutation Have Harmful Effects, But Some Mutations Are Beneficial.
  • Most Mutant Alleles Are Pleiotropic.

CLASSIFICATION OF MUTATIONS

Mutation: Definition, Types, Application
Image Source:- Google By Nature

Mutation Are Classified As-

(1) Spontaneous Mutation:-Spontaneous Mutations Occur Naturally Without Any Apparent Or Known Cause. The Rate Of Spontaneous Mutations Is Very Low. The Possible Source Of Their Origin Are;

  • Normal Cellular Event.
  • Mutagenic Effect Of The Environment.

(2) Induced Mutation:- Mutations Produced Due To Treatment With Either A Chemical Or A Physical Agent Are Called Induced Mutations. The Agent Capable Of Inducing Mutations Is Known As Mutagens. The Process Of Inducing Mutations Through Treatment With A Mutagen Is Known As Mutagenesis, While The Exploitation Of Induced Mutations For Crop Improvement Is Called Mutation Breeding.

MOLECULAR BASIS OF MUTATION

Mutation In A Character Would Generally Be Produced By A Change In The Amino Acid Sequence Of The Protein Determining The Expression Of The Trait. This Change Would Obviously Be Due To A Change In The Base Sequence Of The DNA Molecule Coding For The Protein, Which May Result From 1: Base Substitution, 2:Base Addition Or Deletion, 3:Transposition, 4:Trinucleotide Repeat Expansion.

MUTATOR AND ANTIMUTATOR GENES

Mutator Genes Increase The Frequency Of Spontaneous Mutation Of Other Genes Located In The Same Cell. Mutator And Antimutator Genes Are Known Both In Eukaryotes And Prokaryotes.

 

MUTAGENES

 

Mutations Can Be Induced By A Number Of Agents Called Mutagens. The Different Mutagenic Agents May Be :

(1) Physical Mutagens:- The Different Type Of Radiations Having Mutagenic Properties Are Known As Physical Mutagens. These Radiation May Be A Part Of The Electromagnetic Spectrum Having Shorter Wavelength And Higher Energy Than Visible Light, Or May Be Particulate Radiations Produced By The Decay Of Radioisotopes.

(2) Chemical Mutagens:- A Large Number Of Chemicals Is Reported To Be Mutagenic. Many Agricultural Chemicals, E.G., Several Insecticides, Fungicides, Herbicides, Etc., Have Been Found To Induce Mutations Or Chromosomal Aberrations.

 

DETECTION OF MUTATIONS

 

A Variety Of Tests Have Been Developed For Detection Of Mutations In Organisms Ranging From Viruses And Bacteria, Through Drosophila To Mammals, Including Man. In This Section, Some Techniques For Detection Of Mutations In Bacteria, Drosophila, Plant, And Mice Are Described.

  • Detection Of Mutation In Prokaryote:- Detection Of Mutations Is Very Fast And Relatively Much Simpler In Case Of Bacteria. The Bacterial Cells Are Multiplied In A Complete Medium So That Both Wild Type And Mutant Cell Grow Without Any Restriction.
  • Mutation Detection In Drosophila:- In Drosophila, Several Genetic Stocks Have Been Constructed For The Detetion Of Lethal And Visible Mutations In The X-Chromosome And In Autosomes.

APPLICATION OF MUTATION

 

  • Some Mutations Have Beneficial Effect And Are Useful In Crop Improvement. Mutations In Both Qualitative And Quantitative Traits Have Been Exploited For The Development Of Over 2000 Varieties Of Various Crops.
  • Mutations Have Permitted The Fine Structure Analysis Of Genes As Well As The Determination Of Relationship Between Genes And Protein And Even Some Features Of The Genetic Code.
  • Finally, Induced Mutations Are Being Used For Analysing The Effects Of Various Type Of Known Alterations In DNA On The Expression Of The Concerned Characters.

 

CONCLUSION
  • Mutation In A Gene Allow That Gene To Be Identified And Studied. For Example, The While Eye Locus Was Identified Only After The White-Eyed Mutant Of Drosophila Was Discovered.
  • Such An Analysis Would Be Virtually Impossible In The Absence Of Suitable Mutant Stocks.