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

Determination of proteins and amino acid content in foods, Define Methods o...

Define Methods of Determination of Proteins and Amino Acid Content in Foods? The methods for protein quality evaluation are grouped under the following headings: I) Analytic

Selenium, S e l e n i u m Selenium toxicity due to pollution of ...

S e l e n i u m Selenium toxicity due to pollution of environment has been reported in animals. Contamination of pasture from industries emitting fly ash particularly fo

Of which cells is the nervous tissue constituted, Of which cells is the ner...

Of which cells is the nervous tissue constituted? How is the generic function of this tissue related to the characteristics of the main cell type that forms it? The nervous tis

How muscle contraction intensely increased, To increase the strength of the...

To increase the strength of the muscle work is the muscle contraction intensely increased? An increase in the strength of the muscle work is not achieved by enhance in the inte

Enumerate about the diseases insomnia, Enumerate about the diseases Insomni...

Enumerate about the diseases Insomnia The results from studies of people, who claim that they do not sleep, or wake up frequently from sleep show that their insomnia can have m

Classification, What is omnispective classification

What is omnispective classification

Describe in detail about the huntington''s disease, Describe in detail abou...

Describe in detail about the Huntington's disease The brain of a person who has died as a result of Huntington's disease or Alzheimer's disease will look abnormal even to the

What is molecular biology, Molecular Biology Transgenesis: pro-nucl...

Molecular Biology Transgenesis: pro-nuclear injection of isolated gene into fertilised egg cell, cell divides to form embryo, then embryo implanted into surrogate.

Kingdom fungi, what are the characteristis in species in the phyla division...

what are the characteristis in species in the phyla division

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