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

Which compounds results from cyclization of glucose, Which of the following...

Which of the following compounds results from cyclization of glucose? Select one: a. alpha-D-glucopyronose b. beta-D-glucopyronose c. alpha-D-glucofuranose d. beta-D

Effect on microbial growth of pH, Q. Effect on Microbial Growth of pH? ...

Q. Effect on Microbial Growth of pH? Every microorganism has a minimal, a maximal, and an optimal pH for growth. In general, bacteria grow in the pH range of 6.0-8.0, yeasts 4

Hemorrhagic enteritis, H e morrhagic enteritis in Turkeys The viral e...

H e morrhagic enteritis in Turkeys The viral etiology in turkey poults showing sudden death was first described in1930 and thereafter reported in most turkey-producing areas.

Ecg, Sinus tachycardia is common. ECG abnormalities may reflect the underly...

Sinus tachycardia is common. ECG abnormalities may reflect the underlying coronary artery disease by way of pathological Q-waves, ST-T wave abnormalities. Left ventricular hypertro

Classification of animal world, plz give the classificational chart of anim...

plz give the classificational chart of animals upto speceis level

Microbiology quiz question, Each of the following are true of antimicrobial...

Each of the following are true of antimicrobial therapeutic drugs except A. Non-toxic to host B. Easily broken down by host C. Easily administered D. Limited capacity to elicit

Why do leaves change color, Why do leaves change color? Leave is the fo...

Why do leaves change color? Leave is the food factories of plants. During the spring and summer, leaves are actively making food and they are filled with chlorophyll, which giv

Bacterial diseases-actinobacillosis, Actinobacillosis Synonym   : Woo...

Actinobacillosis Synonym   : Wooden Tongue Causative organism                  : Actinobacillus lignieresii Species affected                   : Ruminants, cattle and s

Week 5 Review Sheet I, How does true motility differ from brownian movement...

How does true motility differ from brownian movement? What morphological structre is responsible for bacteria motility? Why is the wet preparation discarded in disinfectant s

How is the cooling of tissues and organs, Q. How is the cooling of tissues ...

Q. How is the cooling of tissues and organs for medical transplants associated with the effect of temperature upon enzymatic reactions? The molecular degradation during the dec

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