Chapter 28, Problem 9E

Summary Introduction

To explain: The reason why E. coli cells with a defective lacZ gene fail to show galactoside permease activity after the addition of lactose in the absence of glucose.

Introduction: Gene regulation is the process through which the cells control the expression of genes. It controls the genes that are expressed to form a specific functional protein depending on the cell type. There are mechanisms that control the gene expression at different levels based on the binding of RNA polymerase at promoter region and the presence of repressors or activators. In E. coli, an operon consists of the genes in a cluster, and it is transcribed from a promoter. The lac operon is an inducible operon and controls the metabolism of the lactose sugar through β-galactosidase enzyme.