Missense Mutations

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Gene Mutation Random Mutations Vs Directed Mutations Rate of Mutations Effects of Mutations on the Phenotype How Does a Mutation Act? Base Pair Substitutions - Transitions, Transversion, Inversion Framshift Mutations - Deletion, Insertion Effect of Change of One Amino Acid in Phenotype Missense Mutations Codon Changes and Amino Acid Replacments in Haemoglobins Nonsense Mutations Mutation in Termination Codons Silent Codons Genetic Supression Intragenic Suppression Extragenic OR Intergenic Suppression

Missense Mutations

	Missense Mutations - A missense mutation is one which results in the replacement of one amino acid in a polypeptide chain by another. As a result of mutation one base of a codon may be substituted by another base. The changed codon may then code for another amino acid. A missense mutation can be caused by substitution, deletion or insertion.
Missense mutations arising by substitution result in proteins which differ from their normal counterparts only in a single amino acid. Such proteins therefore frequently have normal biological activity. One of the codons for phenylalanine is UUU. A single base substitution (U-->G) changes it to UGU, the codon for cysteine
Thus the protein formed after mutation is identical to the normal protein except that phenylalanine is substituted by cysteine. About half the known human haemoglobins have amino acid substitutions involving single base transversions.

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Suppressor Genes Frameshift Suppressions Molecular Basis of Mutations Spontaneous Mutations Tautomerism Induced Mutations Chemical Mutagens Base Analogues Agents Modifying Purines and Pyrimidines OR Agents Labilize the Bases Agents Producing Distortions in DNA Radiations Types of Mutations