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 changes in mental development of infants, Explain Changes in Mental...

Explain Changes in Mental Development of Infants? There is evidently an increase in the brain size. There is a rapid increase in the number of brain cells in the first 5-6 mont

Coccidioidomycosis, Coccidioidomycosis Coccidioidomycosis is a soil-...

Coccidioidomycosis Coccidioidomycosis is a soil-borne infection of pet, domestic, wild animals and  man. The disease is caused by Coccidioides immitis, a dimorphic fungus wh

Define eggs as a rich source of protein, Define Eggs as a rich source of pr...

Define Eggs as a rich source of protein? Roughly, the chicken egg consists of 11% shell, 31% yolk and 58% white. Liquid whole egg consists of 65% white and 35% yolk. The primar

Environment and health- impact of air and water pollution, Environment and ...

Environment and Health- Impact of Air and Water Pollution Environment includes a host of factors of which air and water are the two major components. Air pollution is caused b

Structural differences between roots and shoots, What are the structural di...

What are the structural differences between roots and shoots? What structures are unique to each?

Types of organization chart, Types of Organization Chart: There are  t...

Types of Organization Chart: There are  two important  types of organization chart.  a)  Vertical i.e.,  from top to bottom.  b)  Horizontal  i.e., from  left to right.

Explain bacterial vaginosis, Bacterial vaginosis  The role of sexual tr...

Bacterial vaginosis  The role of sexual transmission is unclear in bacterial vaginosis, in which normal H2O2-producing Lactobacillus  species are replaced by overgrowth with  G

What do you meant by diabetic ketoacidosis, Q. What do you meant by Diabeti...

Q. What do you meant by Diabetic Ketoacidosis? Diabetic Ketoacidosis (DKA) is one of the acute complications of diabetes mellitus. The name itself implies that there is acidosi

Functions of gluconeogenesis, Functions of Gluconeogenesis The signifi...

Functions of Gluconeogenesis The significance of gluconeogenesis include: 1)  During starvation or during periods of  limited  carbohydrate intake, when  the levels of liv

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