Question

Genes that are involved in turning on or off the transcription of a set of structural genes are called:
A. operator genes
B. redundant genes
C. regulator genes
D. polymorphic genes

Answer 1

Hint: A gene is the primary structural and functional element of heredity. Genes are made out of DNA. Some genes act as instructions for making proteins. However, many genes do not encode for proteins. A human gene can range in size from a few hundred DNA bases to over 2 million bases.

Complete step by step solution:
A gene is also defined by the DNA sequence that codes for the tRNA or rRNA molecule. The structural gene in a transcription unit, on the other hand, could be described as monocistronic (primarily in eukaryotes) or polycistronic by defining a cistron as a stretch of DNA coding for a polypeptide (mostly in bacteria or prokaryotes).
Genes that code for proteins and RNAs, with the exception of regulatory elements like transcription factors, are known as structural genes. They create mRNA, rRNA, and tRNA, which are crucial for both structural and functional purposes, as well as other proteins and enzymes. Any sort of RNA (aside from siRNA and miRNA) and proteins that are not regulatory proteins can be encoded by structural genes. A group of genes known as regulatory genes are responsible for regulating the expression of structural genes. Complex structures make up structural genes.
Regulator, operator, and structural genes form a lac operon. The repressor is created when the regulator gene's m-RNA is translated. In the absence of an inducer, the repressor bonds to the operator and prevents the structural gene from being expressed. When an inducer is present, the repressor binds to it and the operator is not blocked, allowing the structural gene to be expressed. Operator genes are segments of DNA that bind to repressor molecules and prevent the expression of structural genes.

So, option (A) is correct.

Note:
The fundamental genetic component transferred from parent to child, genes are composed of DNA sequences and are organized sequentially at specified sites on chromosomes in the cell nucleus.