Coding region

Coding region refers to the part of a gene or mRNA sequence that directly specifies the amino acid sequence of a protein product. It is a crucial component of the genetic code, playing a vital role in the process of gene expression. The coding region is flanked by untranslated regions (UTRs) at both the 5' and 3' ends of the mRNA, which do not code for proteins but have regulatory roles in translation and mRNA stability.

Overview

The coding region, also known as the open reading frame (ORF), begins with a start codon (usually AUG, which codes for Methionine in eukaryotes and a modified Met in prokaryotes) and ends with a stop codon (UAA, UAG, or UGA), signaling the termination of protein synthesis. The sequence within the coding region determines the linear sequence of amino acids in a protein, which ultimately folds into a specific three-dimensional structure necessary for its biological function.

Gene Expression and the Coding Region

Gene expression involves two main processes: transcription and translation. During transcription, the DNA sequence of a gene is copied into mRNA. The mRNA then undergoes processing, where introns are removed, and the exons are spliced together. The processed mRNA, which includes the coding region, is exported from the nucleus to the cytoplasm for translation.

During translation, the sequence of the coding region is read by the ribosome in sets of three nucleotides, known as codons. Each codon specifies a particular amino acid, and the ribosome assembles these amino acids in the order dictated by the sequence of codons in the mRNA, forming a polypeptide chain that folds into a functional protein.

Significance of the Coding Region

The coding region is fundamental to the flow of genetic information from DNA to protein, embodying the central dogma of molecular biology. Mutations within the coding region can have significant impacts on the structure and function of the encoded protein, potentially leading to diseases. For example, a point mutation that changes a codon to a stop codon can result in a truncated, non-functional protein, leading to genetic disorders.

Genetic Engineering and the Coding Region

In genetic engineering and biotechnology, the coding regions of genes are often manipulated or transferred between organisms to express the desired protein in a target organism. This has applications in medicine, agriculture, and industry, such as the production of insulin, growth hormones, and genetically modified crops.

See Also

• Gene
• mRNA
• Protein synthesis
• Mutation
• Genetic engineering