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

Principle of colorimetric method-2, Define Principle of colorimetric method...

Define Principle of colorimetric method-2, 4 dinitrophenylhydrazine? Ascorbic acid is oxidized to dehydro ascorbic acid by copper (Cu ++ ) ions. 2, 4 dinitrophenyl hydrazine re

Explain mixture in basic chemistry, Explain mixture in basic chemistry? ...

Explain mixture in basic chemistry? Mixtures :  Mixtures are produced by combining two or more substances. In contrast to the substances in compounds, the substances that com

What is electron cloud model, What is Electron Cloud Model ? Electron...

What is Electron Cloud Model ? Electron Cloud Model :  In recent models of the atom, electrons form electron clouds, in which electrons travel in spherical and dumbbell-shap

In which strcture sperm cells go after passing epididymides, Q. After passi...

Q. After passing the epididymides through which structures do sperm cells go until exteriorization? After leaving the epididymis in the testicle sperm cells enters the vas defe

Surface Processes on Earth, Which of the following is not a type of mass mo...

Which of the following is not a type of mass movement that results from the force of gravity? A. Landslide B. Creep C. Deflation D. Mudflow

Scintillation counter, carnt understand its principle and mode of working

carnt understand its principle and mode of working

Explain the colorimetric method glucose estimation, Explain the Colorimetri...

Explain the Colorimetric Method Glucose Estimation? Alkaline copper reduction methods are by far the most commonly used methods for glucose estimation. This time honoured metho

Chest and leg wound complications, Chest and Leg Wound Complications ...

Chest and Leg Wound Complications :  The patients under going CABG are usually elderly, obese and nearly a quater of them are diabetic. So sonic of them get superficial or d

Excretion, What is d excretory organ of the agama lizard

What is d excretory organ of the agama lizard

Slow walking or crawling, Slow walking or Crawling This type of locom...

Slow walking or Crawling This type of locomotion is seen while the animal moves on the substratum. It involves a metachronal rhythm of action in the parapodia. Each fifth or

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