Question

What are the differences between basal, activated, and repressed levels of transcription of a gene?

Answer 1

Basal expression of gene is the minimum level of expression of a gene required so, that it can be maintained inside a cell. For example, a basal level of expression of lac operon is required to encode for permease enzyme. This enzyme leads to the formation of receptor which helps in the uptake of lactose when it is present in the medium.

Activated transcription is the switching on of the gene when it is activated in the presence of specific molecules called as inducer. For example, the expression of lac operon is activated whenever lactose is present in the medium. Lactose molecules act as inducer for the expression of lac operon.

Repressed transcription of the gene is whenever the transcription of gene gets repressed or switched off in the presence of specific molecules called as repressor. For example, the expression of lac operon is switched off whenever the repressor is bound to operator preventing RNA polymerase from transcribing the operon.

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