Chapter 14, Problem 1P

Bacterial genomes frequently contain groups of genes organized into operons. What is the biological advantage of operons to bacteria? Identify the regulatory components you would expect to find in an operon. How are the expressed genes of an operon usually arranged?

Summary Introduction

To review:

The genome of bacteria contains operons that consist of a group of genes. Describe the advantage of these operons to bacteria. Explain the expected regulatory components present in an operon. Also illustrate the arrangement of expressed genes of an operon?

Introduction:

The first operon was discovered in E. coli - “lac operon”- by a group of scientists- Francois Jacob, Andre Michel Lwoff and Jacques Monod in $\text{1960}$. All the genes are regulated for expression via operons. Operons control the gene expression of a group of genes present on it via positive and negative operons. These genes present on an operon are called structural genes. These structural genes are transcribed together. Hence, the genes with operons are either transcribed together or not at all. Each operon will have a single promoter, regulatory gene/ region, operator, and the structural genes.

Explanation of Solution

The gene expression in prokaryotes is completely dependent on the availability of the nutrients in a cell. To save energy and upsurge efficiency, bacteria have operons. The stretch of DNA that regulates the activity of structural genes and a group of genes is referred to as operons. They are regulated by positive and negative gene regulation. A single operon will give expressions of many gene products that save the energy of bacteria and increase the efficiency by gaining large amount of functional proteins. As bacteria have coupled transcription and translation, as soon as the group of genes on an operon is transcribed, they are converted to proteins. The genes are located one after another which allows protein synthesis to be controlled under a single promoter. To control the expression, the operon is switched on or off, according to the need of a cell.

The operon has regulatory components- Promoter, repressor, and activators/inducer.

The expressed genes are arranged after the regulatory region of the gene in a fashion one after another.

Conclusion

Operons in bacteria are described and the subsequent facts related to it are explained.