Question

How many types of operons are there?

Answer 1

Hint: Operon has many structural genes, controlled by a single promoter, operator, and regulator. The operon is made up of mainly three units, namely the operator, promoter, and the structural gene. Usually, prokaryotic operons are transcribed into polycistronic mRNA while eukaryotic operons are transcribed in monocistronic mRNA.

Complete answer:
Cluster of genes that share the same promoter and are labeled as one large mRNA containing multiple cistrons or structural genes. Operons are of two types: Inducible operon - This type of operon is activated where there is an inducer, e.g., Lac operon. Depression operon - It is usually seen in anabolic pathways. The operon is active whereas the functional product or enzyme is normally present in the cell. When the final product reaches its maximum value, the operator shuts down. E.g Trp activity.

Note:
Operons occur mainly in prokaryotes but also in other eukaryotes, like nematodes and fruit flies, Drosophila melanogaster. rRNA strains are common in operons found in many types of eukaryotes which includes chordates also. The operon is made up of a number of genes that are organized under a common promoter and controlled by a common operator. It refers to a set of adjacent structural genes, as well as the regulatory signals that affect structural gene transcription. The regulator of a certain operon is not necessarily coded for by the same operon, this includes repressors, activators, and corepressors. The location and status of operators, regulators, promoters and DNA sequences can point to the effects of common mutations.