Gene mutatiorns, Biology

Assignment Help:

Gene or point mutations occur when the DNA sequence of a gene is altered and the new nucleotide sequence is passed on to the offspring. This occurs either due to addition or deletion or substitution of one or a few nucleoticles. Nucleotide substitutions can be either transitions or transversions. Transitions are replacements of a purine by another purine (A by G or vice versa) or a pyrimidiile by another pyrimidine (C by T or vice versa). Transversions are replacements of a purine by the pyrimidine or vice versa (G or A by C or T or vice versa). We will briefly explain the different types of gene mutations.

a) Substitutions : substitution of one base by another would result in an altered amino acid in a polypeptide chain. For instance triplet AAT in DNA (UUA in mRNA) would specify leucine. But if the first A is ieplaced by C, it will code for valine. Some of the codons are degenerate and substitutions may not alter the amino acid specified. For instance, in the triplet AAT if the first A is replaced by G the amino acid coded would still be leucine. Gene mutations which do not normally affect the active site of a protein will not alter its biological functions. But nucleotide substitutions that change a triplet coding lor an amino acid into a termination codon would produce adverse effects. Once again in AAT, if the second A is replaced hy T (An), the resulting rnRNA codon IJAA is a termination codon. When a termination codon is present in the middle of an mRNA molecule the subsequent codons are not translated and an incomplete polypeptide will be released from ribosomes.


Related Discussions:- Gene mutatiorns

Regulation of the citric acid cycle, Regulation of the Citric Acid Cycle ...

Regulation of the Citric Acid Cycle The citric acid cycle is regulated by certain enzymes and by the availability of ADP.

Explain the ph meter - food microbiology, Explain the pH Meter - Food Micro...

Explain the pH Meter - Food Microbiology? pH is a negative logarithm of H+ ion concentration. Its value remains between 0 and 14. Pure water has a pH of 7 (neutral). pH value l

Sunlight - aquatic habitats, Sunlight - Aquatic Habitats Sunlight is a...

Sunlight - Aquatic Habitats Sunlight is a major limiting factor for water bodies, since light rapidly diminishes as it passes down the column of water. The upper layers of the

Understanding behaviour of diabetic patients, Q. Understanding Behaviour of...

Q. Understanding Behaviour of diabetic patients? Beliefs  Each of us has a set of beliefs that were learned by us when we were young. These include religious beliefs and

How much fats should be taken for management of obesity, How much Fats shou...

How much Fats should be taken for management of obesity? Fats, being a concentrated source of energy need to be restricted. Excess dietary fat promotes much more weight gain th

What is the etiological agent of visceral leishmaniasis, What is the etiolo...

What is the etiological agent of visceral leishmaniasis? How is the disease transmitted and what are its typical manifestations? Visceral leishmaniasis is caused by the protozo

Psychoactive substance use disorders, PSYCHOACTIVE SUBSTANCE USE DISORDERS:...

PSYCHOACTIVE SUBSTANCE USE DISORDERS: Drug: It is derived from a French word 'drogue'. A medical substance used in the treatment of disease. (Taber's  Dictionary).  'Drug d

Explain what is cyanosis and polycythemia, Explain what is Cyanosis and pol...

Explain what is Cyanosis and polycythemia? Cyanosis and Polycythemia: Central cyanosis involving the mucous membranes and trunk along with the lips and extremities in absence

Explain the membrane equilibria, Explain the Membrane Equilibria? A sem...

Explain the Membrane Equilibria? A semipermeable membrane used to separate two liquid phases can, in principle, be permeable to certain species and impermeable to others. A mem

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd