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 volume of 1.20 m naoh solution must we add, You have 875 mL of a 0.37 ...

You have 875 mL of a 0.37 M acetic acid solution. What volume (V) of 1.20 M NaOH solution must you add in order to prepare an acetate buffer of pH = 4.36? (The pKa of acetic acid i

EMBRYOLOGY., WHAT ARE THE TYPES OF EGG ON THE BASIS OF YOLK ?

WHAT ARE THE TYPES OF EGG ON THE BASIS OF YOLK ?

The red data book, The Red Data Book Species judged as threatened are ...

The Red Data Book Species judged as threatened are listed by various agencies as well as by some private organisations. The most cited of these lists is the Red Data Book. It

Explain gonorrhea, Gonorrhea Single doses of cefixime (Suprax) orally ...

Gonorrhea Single doses of cefixime (Suprax) orally or ceftriaxone  (Rocephin)  intramuscularly (IM) are highly effective for uncomplicated anogenital or pharyngeal infection,

State about glycosylated hemoglobin, Glycosylated Hemoglobin (HbA1c) Hb...

Glycosylated Hemoglobin (HbA1c) HbA1c should be done routinely for diabetic patients. It reflects the average glycemic (sugar) control over the previous few months and should b

Fats requirements for ulcerative colitis, Q. Fats requirements for ulcerati...

Q. Fats requirements for ulcerative colitis? Usual foods, which contain fats (invisible or inherent fat), are permitted but not fried foods, as they are not easily digested due

Synthesis of hormones - testies, Synthesis of Hormones - Testies Leyd...

Synthesis of Hormones - Testies Leydig cells and the Sertoli cells are the steroid hormone synthesising cellular sites of the testis. Leydig cells are the major source of the

Hirudinea - feeding and digestion in annelids, Hirudinea - Feeding and Dige...

Hirudinea - Feeding and Digestion in Annelids Hirudinea involves free living and ectoparasitic leeches. Leeches are blood suckers. The digestive system contains a preoral cham

Why we not inundated with bacterial infections, We are told that every surf...

We are told that every surface we touch is teeming with bacterial cells, and bacteria are found in the pools we swim in, the water we wash with, and on the hands of friends. Why ar

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