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 effect on serum proteins during pregnancy, Explain the Effect o...

Explain the Effect on serum Proteins during pregnancy? Total serum protein gradually decreases, along with a sharp decline in albumin. There is reduction in serum albumin along

Define initiation phase - mechanism of protein synthesis, Define Initiation...

Define Initiation phase - mechanism of protein synthesis ? The assembly of a ribosome on an mRNA molecule at the correct start point, the initiation codon. Three initiation fac

Explain membrane filtration technique, Explain Membrane Filtration Techniqu...

Explain Membrane Filtration Technique? Another method used for determining the bacterial number is the filtration technique. The margain figure illustrates the membrane filter

Difference between adrenergic and cholinergic fibre, Difference between Adr...

Difference between Adrenergic and Cholinergic Fibre- S.NO .   1. ADRENERGI C FIBRE   Release nor adrenaline at their CHOLINE

Lead to protein denaturation, Q. What are some factors that can lead to pro...

Q. What are some factors that can lead to protein denaturation? Protein denaturation can be caused by temperature variation, pH change, changes in the concentration of surround

Determine the chemical stage of photosynthesis, Which are the subproducts o...

Which are the subproducts of the photochemical stage that are essential for the chemical stage of photosynthesis? The chemical stage of photosynthesis depends on NADPH and ATP

Explain directly observed therapy of tuberculosis, Directly observed therap...

Directly observed therapy In treating TB, poor adherence to therapy is the most important cause of treatment failure and is associated with emergence of drug resistance. Medica

What is implant therapy, What is Implant therapy Successful implant th...

What is Implant therapy Successful implant therapy requires systematic thorough and meticulous planning to determine the ultimate prognosis and end result that will satisfy th

Disorders of liver, DISORDERS OF LIVER: In the foregoing  sections and...

DISORDERS OF LIVER: In the foregoing  sections and sub-sections we have discussed about the common disorders of upper and lower gastrointestinal  tract. Now we shall discuss

Why do ribosomes move along mrna during translation, Why do ribosomes move ...

Why do ribosomes move along mRNA during translation? During translation the ribosome always exposes two mRNA codons to be translated by moving along the mRNA. When a peptide bo

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