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 the liver organ, Explain the Liver organ? The liver is the larg...

Explain the Liver organ? The liver is the largest internal organ in the human body. It lies just below the diaphragm in the upper right area of the abdominal cavity. It is an i

An insect collecting net, An insect collecting net A useful insect net ...

An insect collecting net A useful insect net can be made from a round stick such as a broom or mop handle, some heavy wire and mosquito netting or cheese cloth. Bend a heavy pi

What is fermentation, What is fermentation? Name any two organic compounds ...

What is fermentation? Name any two organic compounds formed in this process

Embryology and histology, Embryology: Embryology (from Greek words embryon...

Embryology: Embryology (from Greek words embryon which means unborn embryo and logia which means study) is a branch of science which deals with the development of an embryo starti

Show the anatomical evidence, Q. Show the Anatomical Evidence? Anatomy ...

Q. Show the Anatomical Evidence? Anatomy is the study of the structure, organisation and development of cells and tissues of plants and animals. For over a century taxonomists

Electrophoresis gel to load 60, Assume your tilapia fish muscle homogenate ...

Assume your tilapia fish muscle homogenate has a protein concentration of 5769 ?g/ml. You take 32.5 ?l of this fish homogenate, mix it with 12.5 ?l sample buffer and 5 ?l reducing

Explain congenital syphilis, Congenital Syphilis  A positive serologica...

Congenital Syphilis  A positive serological test for syphilis in a newborn without stigmata of syphilis may be due either to passive transfer of maternal antibodies or to prena

Fossil history of horse, Evolution of Horse - Credit to Prof. C. Marsh...

Evolution of Horse - Credit to Prof. C. Marsh (1879) of Yale University for complete work.   S.No   Fo ssil/Genus   Period

Ameoba, locomotion in amoeba

locomotion in amoeba

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