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

Fruits why not glucose, Sucrose is commonly used to preserve fruits why not...

Sucrose is commonly used to preserve fruits why not glucose? Ans) Glucose is reactive due to its open-chain form having an aldehyde group.

Explain class adverse effects of protease inhibitors, Explain Class adverse...

Explain Class adverse effects of Protease inhibitors   Many protease inhibitors can cause gastrointestinal distress, increased bleeding in hemophiliacs, hyperglycemia, insulin r

An a=t mispairing leads to an a=c substitution, An A=T mispairing leads to ...

An A=T mispairing leads to an A=C substitution. The other DNA helix will contain a(n) __ pair. a. A=C b. A=T c. G=C d. B=Q e. T=T Can you also explain it please so if I'm ask

Coordination of digestion, Coordination of Digestion You have learnt ...

Coordination of Digestion You have learnt that digestion is a process in which large food molecules arc broken down step by step into their constituents. In primitive metazoa

PLASMODIUM LIFE CYCLE, elucidate a life cycle of a plasmodium that causes m...

elucidate a life cycle of a plasmodium that causes malaria

Define energy needs during pregnancy period, Define Energy needs during pre...

Define Energy needs during pregnancy Period? Two factors determine energy requirements: increase in mother's basal metabolism to support the work required for foetal growth and

Vertebrate eye - adult eye, Vertebrate Eye - Adult Eye There are no m...

Vertebrate Eye - Adult Eye There are no main differences in the structure or composition of the eyes among different vertebrates. This should be clear to you from the diagram

Morphological differences between monocot and dicot plants, Q. What are the...

Q. What are the major morphological differences between monocot plants and dicot plants? The main separation criteria between monocots and dicots are: number of cotyledons (see

Explain human leucocyte antigen complex, a) Explain the polygonum type of e...

a) Explain the polygonum type of embryo sac. Why is it generally referred to as monosporic ? b) Explain human leucocyte antigen complex? Describe its role in organ transplantati

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