What is the Difference Between Gene Expression and Gene Regulation

The main difference between gene expression and gene regulation is that the gene expression is the process which synthesizes a protein by using the information in a gene whereas gene regulation is the process of controlling the rate and the manner of gene expression. Furthermore, the two steps of gene expression are transcription and translation while the expression of genes is regulated at each level of gene expression.

Gene expression and gene regulation are two types of simultaneous processes, which allow the synthesis of gene products as needed by the cell.

Key Areas Covered

1. What is Gene Expression
     – Definition, Steps, Importance
2. What is Gene Regulation
     – Definition, Mechanisms, Importance
3. What are the Similarities Between Gene Expression and Gene Regulation
     – Outline of Common Features
4. What is the Difference Between Gene Expression and Gene Regulation
     – Comparison of Key Differences

Key Terms

Gene Expression, Gene Regulation, Structural Genes, Transcription, Translation

What is Gene Expression

Gene expression is the cellular mechanism responsible for the synthesis of gene products based on the information on a gene. Generally, a gene is composed of a nucleotide sequence made up of codons representing each amino acid of a functional protein. The genes which code for a functional protein are known as structural genes. The gene products of the rest of the genes are the non-coding RNA (tRNA or rRNA), which are not translated into an amino acid sequence of a functional protein. Therefore, these genes are known as RNA genes. However, exons and introns are the structural elements of both types of genes, involved in gene expression.

Figure 1: Process of Gene Expression

Furthermore, the two steps of gene expression are transcription and translation. Transcription is the first step of gene expression. It involves the synthesis of an RNA molecule based on the information coded by a gene. Here, structural genes are responsible for the production of an mRNA molecule while RNA genes are responsible for the production of either tRNA or rRNA. Significantly, the main function of these non-coding RNA is to help in translation, which is the second step of gene expression. During translation, an amino acid sequence of a functional protein is synthesized based on the information encoded by the mRNA molecule. In eukaryotes, transcription occurs inside the nucleus and RNA polymerase is the enzyme which catalyzes the event. But, translation occurs in the cytoplasm with the help of ribosomes. In prokaryotes, both transcription and translation occur inside the cytoplasm.

What is Gene Regulation

Gene regulation is another cellular mechanism related to gene expression, controlling the amount and the type of gene products synthesized by the gene expression. Each and every step of gene expression can be regulated by various mechanisms. It starts at the transcription initiation, proceeds through RNA processing, and ends up with the post-translational modifications. Some of the regulated stages are chromatin domains, transcription, post-transcriptional modifications, RNA transport, translation, and mRNA degradation.

Figure 2: Regulation of Gene Expression Based on an External Stimuli

Moreover, regulation of gene expression is important to control the developmental process, response to environmental stimuli or an adaptation to a novel environmental condition. Some of the genes in the genome are expressed continuously since their function is essential for the basic metabolic functioning of an organism. However, specific genes may only be expressed when needed by the cell. Also, the number of gene products can be controlled by the regulation of gene expression based on the requirements of the cell. Chromatin structure is a key factor in transcription regulation. Through histone modifications directed by DNA methylation, euchromatin and heterochromatin can be interconverted to regulate transcription. Also, the structural elements of a gene including the transcription initiation site, promoter, enhancers, and silencers regulate the transcription of a gene. Transcription factors bind to the enhancer and silencer regions to control transcription. In addition, RNA processing events including alternative splicing and mRNA stability can be regulated. Sequestration of the RNA transcript is another post-transcriptional regulation event. Also, the rate of translation and various post-translational modifications of proteins are regulated in order to produce the required types of proteins by the cell.

Similarities Between Gene Expression and Gene Regulation

• Gene expression and gene regulation are two processes involved in the synthesis of gene products.
• Both are important in the synthesis of gene products based on cellular needs.

Difference Between Gene Expression and Gene Regulation

Definition

Gene expression refers to the process by which the instructions in our DNA are converted into a functional product, such as a protein, while gene regulation refers to the process involved in turning genes on and off to ensure the appropriate expression of genes at the proper times. Thus, this is the main difference between gene expression and gene regulation.

Steps/Mechanisms

The two steps of gene expression are transcription and translation while the regulation of gene expression occurs either at the transcriptional, post-transcriptional, translational, and post-translational levels.

Structural Elements

The structural elements subjected to gene expression are exons and introns while the structural elements involved in gene regulation are the transcription initiation site, promoter, enhancers, and silencers. Hence, this is another difference between gene expression and gene regulation.

Importance

Their importance is also another major difference between gene expression and gene regulation. Gene expression is responsible for the synthesis of gene products while gene regulation is responsible for controlling the amount and the type of gene products based on the requirements of the cell.

Conclusion

Gene expression is the process by which the information on genes is used to synthesize a gene product. The two steps involved in gene expression are transcription, in which the nucleotide sequence of a gene is used to synthesize an RNA molecule, and translation, in which the information on an RNA is used to synthesize a functional protein. In contrast, gene regulation is the process which controls the amount and the type of gene products based on the requirements of the cell. It occurs in each step of gene expression. Therefore, the main difference between gene expression and gene regulation is the mechanism and the importance.

References:

1. “Gene Expression and Regulation.” University of Leicester, 17 Aug. 2017, Available Here.

Image Courtesy:

1. “Gene expression eukaryote” By CKRobinson – Own work (CC BY-SA 4.0) via Commons Wikimedia  
2. “Regulation of gene expression by steroid hormone receptor” By Ali Zifan 03:07, 10 July 2016 (UTC) – Own work; Used information from:Campbell Biology (10th Edition) by: Jane B. Reece & Steven A. Wasserman. (CC BY-SA 4.0) via Commons Wikimedia 

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