Microbiology Procedure

Index >> Regulation of Protein Synthesis - Operon >> Mutation in the Operon

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Regulation of Protein Synthesis - Operon Structural Genes Operator Genes Promoter Gene Regulator Gene Control Mechanism - Induction Control Mechanism - Repression Inducible System Repressible System Negative Control of Protein Synthesis Positive Control of Protein Synthesis Mutation in the Operon

Mutation in the Operon

	Mutation in the Operon - It is consists of divide into two types. They are follows, 1. Regulator gene . A mutation taking place in a regulator gene may produce a non-functional repressor protein with a changed amino acid sequence. Such mutants are called constitutive mutants. A mutant repressor is not able to bind to the operator gene. Under such conditions the action of RNA polymerase would not be blocked. The structural genes transcribe mRNA and enzyme synthesis occurs regardless of need. Such enzymes are called constitutive enzymes.
2. Promoter gene. A mutation in the promoter may either totally prevent attachment of RNA polymerase or may increase or decrease attachment. When attachment is totally prevented, the structural genes cannot transcribe mRNA and there is no enzyme synthesis. An "up promoter" mutation which permits more rapid attachment of RNA polymerase molecules results in an increased rate of enzyme synthesis.
Conversely, a "down-promoter" mutation which decreases the rate of RNA polymerase attachment results in reduced enzyme synthesis. There are also some promoter mutations which reduce the requirement of cyclic AMP.

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Regulation of Gene Activity in Eukaryotes Frenster's Model of Gene Regulation Nonhistone Protein as Derepressors Britten Davidson Operon Operator Model Sensor Genes Producer Genes Integrator Genes Receptor Genes

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