Difference between Structural and Regulatory Genes

Structural Genes

Structural genes are the genes that code for proteins and RNAs except regulatory factors, such as transcription factors. They synthesise proteins and enzymes that are important for structural and functional uses, such as mRNA, rRNA and tRNA.

In prokaryotes, the structural genes are present sequentially, and regulated by a single promoter and operator. However, in eukaryotes they are mostly found in the coding regions.

Clinically, the structural genes can be studied to find out any genetic variations or mutations in the sequences.

Regulatory Genes

Regulatory genes are the genes that code for repressor proteins in prokaryotes. These regulatory proteins control the level of expression of the structural genes. The regulatory genes include miRNA and siRNA.

The regulatory sequences are present several kilo bases far from the initiation site of transcription. They are used clinically to activate or repress the expression of a particular gene.

Structural vs Regulatory Genes

Structural Genes

Regulatory Genes


Structural genes are those genes that code all the proteins in a genome except regulatory genes.

Regulatory genes are those genes that code for proteins or factors that control the expression of structural genes.


In prokaryotes, structural genes are present in a sequence called operon. However, in eukaryotes, structural genes are found in the exon regions.

Regulatory genes are usually found a bit far from the structural genes, say, 500 base pairs apart, and are mostly found in the intron regions.

Genes Encoded

mRNA, rRNA, and tRNA

miRNA and siRNA


It encodes all the proteins required for structural and functional uses.

It encodes factors / proteins that control the expression of structural genes.


Structural genes of the lac operon such as lac A, lac Y and lac Z.

Regulatory genes are lac I and CAP.

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Frequently Asked Questions

What are regulator genes and why are they important?

Regulator genes are important as they help in controlling the expression of structural genes. Some proteins are not required all the time, so the genes synthesising them need to be turned off, this is done by the regulator genes.

What is the difference between gene expression and gene regulation?

Gene expression is the phenomenon of synthesis of a protein by the process of transcription and translation. On the other hand, gene regulation is the process of controlling the expression of that protein by an activator or repressor molecule.

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