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

What is sodium-potassium pump, Sodium-potassium pump A. The net flux of...

Sodium-potassium pump A. The net flux of sodium is from a region of high sodium concentration to a region of low sodium concentration. B. The net flux of potassium is from a

Proteins, what is proteins?properties of protein

what is proteins?properties of protein

What is the formula for photosynthesis, What is the formula for photosynthe...

What is the formula for photosynthesis? H 2 O + 6CO 2 + Light Energy ----> C 6 H 12 O6+ 6O 2 6 molecules of water + 6 molecules of carbon dioxide --->1 molecule of glucose

What are the three major types of rna, Q. What are the three major types of...

Q. What are the three major types of RNA? What is meant by heterogeneous RNA? Messenger RNA, or mRNA, transfer RNA, or tRNA, and ribosomal RNA, or rRNA, are the three main type

Explain nucleotides, Nucleotides Compounds  consisting of a  nitrogenou...

Nucleotides Compounds  consisting of a  nitrogenous  base,  a  pentose sugar and a phosphate group.

Regulation of blood glucose level, REGULATION OF BLOOD GLUCOSE LEVEL Va...

REGULATION OF BLOOD GLUCOSE LEVEL Various levels of regulation are exerted at substrate level, hormonal level, enzymatic level and at organ level on carbohydrate  metabolism  s

Explain indications for surgery of total anomalous, Explain Indications for...

Explain Indications for Surgery of Total Anomalous pulmonary Venous Connection ? Once TAPVC is diagnosed in a neonate with symptoms, operation should be undertaken immediately.

Photosynthesis carbon dioxide is improved to form glucose, Q Why is it said...

Q Why is it said that during photosynthesis carbon dioxide is improved to form glucose? During photosynthesis carbon dioxide is energetically improve with hydrogen from water.

Chromosome jumping, Chromosome jumping is the technique whereby one begins...

Chromosome jumping is the technique whereby one begins with a piece of DNA from one area of a chromosome, and obtains clones from nearby areas without cloning everything in betwee

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