Explain the contribution of the scientists: François Jacob and Jacques Monod.

(N/A) François Jacob,a geneticist,and Jacques Monod,a biochemist,were the first to elucidate the mechanism of gene regulation in bacteria. They proposed the $Lac$ operon model in $1961$. This model explains how the expression of genes involved in lactose metabolism is regulated by the presence or absence of lactose in the environment. Their work provided a fundamental understanding of how genes are switched 'on' or 'off' in response to environmental stimuli,which is a cornerstone of molecular biology.