Biotech Articles
Publish Your Research Online
Get Recognition - International Audience

Request for an Author Account   |   Login   |   Submit Article
 
 
HOME FAQ TOP AUTHORS PUBLISH ARTICLE Nexa Collections (Advt.)
 
 

Mutations: Suppression or Intergeneric Reversion

BY: Shivika Bhatnagar | Category: Biology | Submitted: 2011-12-17 05:36:51
       No Photo
Article Summary: "If the mutational changes occur in a second gene, it eliminates or suppresses a mutant phenotype which is called suppression or intergeneric reversion. This type of suppression has been studied carefully with conditional mutation which develops wild type phenotypes on certain conditions and produces mutant phenotype in other con.."


Share with Facebook Share with Linkedin Share with Twitter Share with Pinterest Email this article
     


If the mutational changes occur in a second gene, it eliminates or suppresses a mutant phenotype which is called suppression or intergeneric reversion. This type of suppression has been studied carefully with conditional mutation which develops wild type phenotypes on certain conditions and produces mutant phenotype in other conditions. The major class of this mutation is called suppressor sensitive mutation. It acts like wild type when a suppressor molecule is present. For example, a phage mutant can grow in one strain. Supressor sensitive mutations are of two types, non-sense (chain termination) mutation and missense (amino acid substitution) mutations.

Non-sense Mutations

Most of the mutations affect only one base pair in a given location, therefore, these mutation are called point mutation or gene mutation. There are several types of point mutations. Non-sense mutation is one type of point mutation. There are 64 codons that code for amino acid out of which three codons (UAA, UAG, UGA) are known as termination codons that do not code for any amino acid. If any change occurs in any codon, it brings about changes in amino acids which specify an amino acid to termination codon. This process is called non-sense mutation. For example, UAC codes for tyrosine. If it undergoes base substitution (C-G), it becomes UAG i.e. a termination codon. This results in synthesis of incomplete polynucleotide chain which remains inactive. Only a fragment of wild type protein is produced which has a little or no biological function unless mutations bring about drastic change in expression of phenotypic characters because in this mutation the structure and function of enzymes are changed.

Missense Mutation

Missense mutation is the second type of point mutation. When one amino acid in a polypeptide chain is replaced by the other amino acid, this type of mutation is known as missense mutation. For example, if a protein valine (non- polar) has been mutated to aspartic acid (polar) due to loss of activity, it can be restored to the wild type phenotype by a missense suppressor that substitutes alanine (non-polar) for asparatic acid.

A missense mutation occurs by insertion, deletion or substitution of a single base into a code, for example the codon GAG specifying glutamic acid could be changed to GUG which codes for valine. Missense mutation that arises from substitution , synthesizes proteins that differs from the normal protein by a single amino acid. Substitution occurs in three different ways:1. A mutant tRNA may rceognise two codons perhaps by a change in anticodon loop, 2. A mutant tRNA can be recognized by a wrong aminoacyl synthetase and be misacylated, and 3. A mutant synthetase can change a wrong tRNA molecule. However, if a suppressor that substitute alanine for aspartic acid worked with 20% efficiency, every protein to which a cell synthesizes atleast one aspartic acid is replaced. In this situation a cell probably cannot survive.

Silent Mutation is another type of point mutation which could not be detected until the nucleic acid sequencing is done. Any change in gene does not affect the phenotypic expression because the code is degenerate i.e. more than one code specify an amino acid. For example, if the codon CGU is changed to CGC, still it would code for arginine. Similarly, both AAG and AAA specify alanine. If the codon AAG is changed to AAA, the latter codon will still code for lysine even after change in base sequence of DNA. This mutation is of silent type because even after change in base sequence of DNA, there is no change in the amino acid sequence and expression of phenotype characters.

Frameshift mutation arises from insertion or deletion of one or two pairs within the region of the gene. It is also a gene mutation. It is very deleterious and yields mutant phenotypes resulting from the synthesis of non-functional proteins. If frameshift occurs near the end of the gene or there occurs a second frameshift down stream from the first and restores reading frame, the phenotypic effect would not be drastic.

About Author / Additional Info:


Search this site & forums
Share this article with friends:



Share with Facebook Share with Linkedin Share with Twitter Share with Pinterest Email this article

More Social Bookmarks (Digg etc..)


Comments on this article: (0 comments so far)

Comment By Comment

Leave a Comment   |   Article Views: 5055



Additional Articles:

•   Journey to Bacillus Thuringiensis (BT) Crops

•   The New and Easy Way to Obtain P450-metabolites and N-glucuronides For Metabolit

•   Ultrafiltration in Vaccine Industry

•   Doors Effects of Clenbuterol




Latest Articles in "Biology" category:
•   Wonderful World of Microorganisms and Their Role in Human Life.

•   Molecular Biology Techniques

•   Process of Reproduction in Bacteria

•   Importance of Microorganisms in the Ecosystem

•   Starting From the Basics: DNA Extraction

•   Agrobacetium-Mediated Transformation Protocol

•   Sucrose Regulating Photosynthesis

•   Nitrogen Fixation: Genes Involved and the Infection Process

•   Functional Genomics: A Tool in Genetic Engineering

•   Plant Tissue Culture and Its Applications

•   Harmful Effects of Mold and Their Prevention

•   Gel Electrophoresis in Molecular Biology

•   Extraction of Phytochemicals

•   Applications of Thin Layer Chromatography

•   Beneficial and Harmful Bacteria

•   Calvin Cycle Regulation and Effect on Photosynthesis

•   How a Baby Develops Inside Mother's Womb: From an Embryo to a Child

•   Apoptosis (or cell suicide) : Process and Types

•   Neurotransmitters and its types



Important Disclaimer: All articles on this website are for general information only and is not a professional or experts advice. We do not own any responsibility for correctness or authenticity of the information presented in this article, or any loss or injury resulting from it. We do not endorse these articles, we are neither affiliated with the authors of these articles nor responsible for their content. Please see our disclaimer section for complete terms.
Page copy protected against web site content infringement by Copyscape
Copyright © 2010 biotecharticles.com - Do not copy articles from this website.

ARTICLE CATEGORIES :
Agriculture Bioinformatics Applications Biotech Products Biotech Research
Biology Careers College/Edu DNA Environmental Biotech
Genetics Healthcare Industry News Issues Nanotechnology
Others Stem Cells Press Release Toxicology  


  |   Disclaimer/Privacy/TOS   |   Submission Guidelines   |   Contact Us

web
statistics