Chapter 10, Problem 1RQ

Summary Introduction

To review:

The regulatory mechanisms working at the DNA (deoxyribonucleic acid) level, transcriptional level, translational level, and post-translational level.

Introduction:

Gene expression is the process by which the information encoded in the genes is used to synthesize a functional gene product. This can be controlled at various levels such as the DNA level, transcriptional level, translational level, and post-translational stage. Regulation is required to decrease or increase the formation of specific proteins or RNA (ribonucleic acid).

Explanation of Solution

The regulatory mechanisms occurring at the DNA level are as follows:

1. Gene inversion on/off switch: In this mechanism, there is the flipping of orientation of a gene or segment of DNA in the chromosome.

2. Slipped strand-mispairing: It is a type of mutation process occurring at the time of replication of DNA. It results in the mispairing of complementary bases due to denaturation and displacement of DNA strands.

The regulatory mechanisms present at the transcriptional level are as follows:

1. Repressors and activators are present that interact with the DNA. Activators are responsible for complementing the functions of the enzymes involved in transcription while the repressors inhibit or suppress the transcription process.

2. The sRNAs (small RNAs) may attach to the mRNAs (messenger RNAs) and interfere with the activities of the RNases.

The best example of regulation at translational level is the attenuation process. It is a regulatory mechanism that is present in certain bacterial operons and leads to premature termination of the transcription process. The regulatory mechanisms at post-translation level include chemical modifications of the enzymes through the process of phosphorylation, methylation, acetylation, or cleavage. The modifications either enhance or reduce the activities of the enzymes.