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

Science in the ancient world, Science in the ancient  world: We have e...

Science in the ancient  world: We have explained why we should study the history of science and what we mean by the history of science. We have seen what science is like in t

ATP FORMATION, what compound is phosphorylated for ATP? what is the resulti...

what compound is phosphorylated for ATP? what is the resulting compound when ATP releases energy

Proestrus - estrous cycle, Proestrus - Estrous cycle This precedes the...

Proestrus - Estrous cycle This precedes the next heat and is characterised by functional involution of the corpora lutea and preovulatory swelling of the follicles. Fluid coll

Water-soluble vitamins for school children and adolescents, Determine Water...

Determine Water-soluble vitamins needs of school children and adolescents? The suggested requirements are given in Table 15.2 (ICMR 1990). Thiamine is computed as 0.5 mg/1000 K

Explain selective and differential culture media, Explain Selective and Dif...

Explain Selective and Differential Culture Media? These are used for isolation of specific organisms. These are designed to isolate a group of closely related organisms and dif

What is the difference among animal and bacterial cells, Concerning the pre...

Concerning the presence of the nucleus what is the difference among animal and bacterial cells? Animal cells (cells of living beings of the kingdom Animalia) have an interior m

Explain deep fat frying method, Deep fat frying Deep fat frying, as you...

Deep fat frying Deep fat frying, as you may already know, is the method which involves cooking food in hot fat/oil. The fat immediately surrounds the food and cooks it from all

What is bilateral symmetry system, What is Bilateral Symmetry system? T...

What is Bilateral Symmetry system? To review: all animals besides the sponges (Phylum Porifera) belong to the Eumetazoa. There are two groups within the Eumetazoa that possess

Define basic terminology in relation to nutritional needs, Define Basic Ter...

Define Basic Terminology in Relation to Nutritional Requirements? By now you would have a good understanding that nutrient requirements are affected by a number of factors and

Implementation of the plan in diabetes mellitus, Q. Implementation of the P...

Q. Implementation of the Plan in diabetes mellitus? You have helped the client to find out an alternative solution and to develop a plan to solve the problem. Now, it has to be

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