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

Classification, Tricks of learn a classification (molusca,arthopoda,prifera...

Tricks of learn a classification (molusca,arthopoda,prifera etc.)

Explain the culture media and its types, Explain the Culture Media and Its ...

Explain the Culture Media and Its Types? A culture medium (Pl. media), we already know, is a solid or liquid preparation containing all the nutrients required by microorganisms

Extractive use of biodiversity, Q. Extractive use of biodiversity? This...

Q. Extractive use of biodiversity? This includes direct use such as harvesting of wild plant species for use as food, fuel, fodder, fibre, shelter or medicine and hunting anima

Define the historical process of spatial processes, Define the Historical P...

Define the Historical Process of Spatial processes? In year 1952 Alan Turing developed his theory of the generation of pattern in systems of reaction diffusion equations, now k

Determine the function of monomeric enzymes, Determine the fuction of Monom...

Determine the fuction of Monomeric enzymes Monomeric enzymes include, pepsin, like the pancreatic serine proteases, plays a role in the digestion of proteins eaten by mammals.

Phycomycosis (zygomycosis), Phycomycosis (zygomycosis) Zygomycosis (pr...

Phycomycosis (zygomycosis) Zygomycosis (previously known phycomycosis) involves fungi belonging to genera Mucor, Rhizopus, Absidia, Entomophthora, Mortierella and Basidiobolou

Transplantation, Transplantation - It is implanting of a living or p...

Transplantation - It is implanting of a living or preserved tissue or organ from one site to another side in the same individual or from one individual called donor to recip

Reduction in the birth rate, State three conditions in a society which coul...

State three conditions in a society which could contribute to a reduction in the birth rate. Birth rate might be decreased by (i) later marriages (as smaller families), (

Define single beam and double beam optical path, Define Single Beam and Dou...

Define Single Beam and Double Beam Optical Path? In simpler instruments, a single beam of light passes through the cuvettes and reaches the detector whereas in the double beam

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