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 rickets, Explain Rickets Rickets:- A condition in children du...

Explain Rickets Rickets:- A condition in children due to vitamin D deficiency.

What are rna polymerase subunits, Each of the three eukaryotic RNA polymera...

Each of the three eukaryotic RNA polymerases has more subunits or 12 and so these are big complex enzymes. The genes encoding some of the subunits of each  eukaryotic  enzyme  show

Molecular biology on which dna fingerprint is based, What is the fact of Mo...

What is the fact of Molecular Biology on which DNA fingerprint is based? The DNA fingerprint, the method of individual identification using DNA, is based on the fact that the D

Right atrial pressure, RAP can be determined semiquantitatively by assessi...

RAP can be determined semiquantitatively by assessing collapse of the inferior vena cava during inspiration. The inferior vena cava is imaged subcostally and its diameter is exa

Explain the evolution of the vascular plant body, Explain the Evolution of ...

Explain the Evolution of the Vascular Plant Body? Vascular Plant anatomy reflects adaptation to life on land. In an aquatic environment, the photosynthetic surfaces are support

How are gases exchanged in sponges, Q. How are gases exchanged in sponges? ...

Q. How are gases exchanged in sponges? The gas exchange in sponges happens by diffusion from the exterior to the cells that absorb molecular oxygen and liberate carbon dioxide.

Digestive system, identify structural modifiactions of the stomach and smal...

identify structural modifiactions of the stomach and small intestine walls that enhance the digestive processes in these regions

What is the approximate number, What would be the approximate number of ami...

What would be the approximate number of amino acids of a protein with a mass of 203 kd? Assume an average molecular weight for amino acids of 110 grams/mol.

How dissimilar is the gametogenesis in women and in men, Concerning events ...

Concerning events during the periods of life how dissimilar is the gametogenesis in women and in men? The formation of spermatogonia in men takes place during the embryonic per

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