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

Explain about colloidal system, Explain about colloidal system A colloi...

Explain about colloidal system A colloidal system, on the other hand, is a heterogeneous system. The material that forms the base of the system is called  the dispersion medium

What factor contributed to the current variations, According to the theory ...

According to the theory of natural selection, what factor below contributed to the current variations in beak sizes of finch species on the Galapagos Islands? a. Finches dispersed

Define water losses by visible perspiration, Define water losses by visible...

Define water losses by visible perspiration? The water losses by visible perspiration are highly variable; the amount could be as high as 4L in hot climate or during strenuous

How to increase in the amount of glucokinase in liver, How to increase in ...

How to increase in  the amount of glucokinase in liver Consumption of a meal rich in carbohydrate  or administration  of insulin initiate an increase in  the amount of glucokin

Explain the ebb-phase of stress response, Explain the Ebb-Phase of Stress R...

Explain the Ebb-Phase of Stress Response? This occurs immediately following injury and lasts for approximately 24-hours. The so-called ebb phase, which is the early phase of th

Define key concepts and facts of polysaccharides, Define Key Concepts and F...

Define Key Concepts and Facts of Polysaccharides? 1. All polysaccharides contain several monosaccharide units. 2. All monosaccharide units are joined to each other by glycosidi

Carrier ions like na+ facilitate the absorption of substance, Carrier ions ...

Carrier ions like Na+ facilitate the absorption of substances like: 1. amino acids and glucose 2. glucose and fatty acids 3. fatty acids and glycerol 4. fructose and so

The statement is true or false, True or false, adaptations are the result o...

True or false, adaptations are the result of finding the best or only solution to a given problem a species faces.

Vitamin, fish liver oil is rich in which vitamin ???

fish liver oil is rich in which vitamin ???

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