If a set of genes is induced in the presence of the controlling substance, it is referred to as positive control.
Genes are known as the basic unit of heredity. They contain a sequence of nucleotides which is responsible for the formation of a gene product that is functional.
The functional gene product is formed by the process of gene expression. In gene expression, there is first the formation of RNA from DNA by the process of transcription and then there is formation of a functional gene product by the process of translation from the RNA.
In the positive control, the expression of genes takes place only in the presence of a controlling substance that is known as an activator.
The set of genes are induced only in the presence of an activator, when there is positive control. The gene is not expressed in the absence of the controlling substance.
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