Question

Contrast constitutive genes from inducible genes. Give two examples for each.

Answer 1

I'm a little unsure of your terminology.

I think by constitutive genes, you mean those that are always being transcribed and translated into protein products and by inducible genes, you mean those that are transcribed and translated in response to specific conditions and stimuli from the cell.

Constitutive genes code for proteins which are absolutely essential to the cell. I call them "housekeeping genes" because they perform the basic functioning activities of the cell. The metabolic proteins in the TCA cycle and porins are examples of products of constitutive genes.

By contrast, inducible genes are transcribed in response to specific stimuli. My favorite is the battery of genes controlled by a transcription factor called Hypoxia Inducible Factor (HIF) which is up regulated by oxygen deficits and includes various glycolytic enzymes and proteins which mediate blood vessel growth. Other inducible genes code for proteins involved in nitric oxide signalling.

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