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

What is the impaired healing, Impaired Healing and Infection Because of Imp...

Impaired Healing and Infection Because of Improper Flap Design The oral field in itself is a contaminated area due to the presence of the normal oral microflora. Improper flap

Etiological factor of diverticular disease, Q. Etiological factor of divert...

Q. Etiological factor of diverticular disease? The causes of diverticular disease are not certain, but several factors may contribute to changes in the wall of the colon. These

What is autophagic intracellular digestion?, Autophagic intracellular diges...

Autophagic intracellular digestion is the cellular internal digestion of waste and residual materials. In general it is completed by lysosomes. Autophagic intracellular digestio

Why are grasshopper is said to show male heterogamity, a) Why are grasshopp...

a) Why are grasshopper and Drosophila said to show male heterogamity? Describe. b) Define female heterogamity with the help of an example.

What is aneuploidy, What is aneuploidy? What are the conditions caused by t...

What is aneuploidy? What are the conditions caused by the aneuploidies? The Aneuploidy is an abnormal number of chromosomes in the cells of an individual. The major aneuploi

Organization levels of life, Q. Define the Organization Levels of Life? ...

Q. Define the Organization Levels of Life? Ans. The cell is the basic unit of life - the smallest unit that can carry on all the processes of life. Organisms that consist of a

Explain phylum zooflagellata, Phylum Zooflagellata (Animal Flagellates)...

Phylum Zooflagellata (Animal Flagellates) 1) At some stage of life-cycle they have one or more flagella. 2) They feed heterotrophically by absorption or phagocytosis, and

Explain about the spinal trauma, Explain about the Spinal Trauma? Spina...

Explain about the Spinal Trauma? Spinal trauma or spinal cord injury, commonly clue to accidents, fills, sports injury can result in serious disabling consequences. The spinal

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