Coding strand

Process of DNA transcription

Coding strand refers to one of the two strands of DNA in a double helix structure that carries the genetic information necessary for protein synthesis. Unlike its counterpart, the template strand, the coding strand has the same sequence as the mRNA (messenger RNA) transcript produced during transcription (with the exception that thymine (T) in DNA is replaced by uracil (U) in RNA). This strand is also known as the sense strand, non-template strand, or positive strand. The coding strand is crucial in the process of gene expression, serving as a reference for the creation of an mRNA transcript that will later be translated into a protein.

Overview

During the process of gene expression, a particular segment of the DNA is transcribed into RNA by the enzyme RNA polymerase. The RNA polymerase binds to the template strand of the DNA, which is complementary to the coding strand, and synthesizes a single-stranded RNA molecule. This RNA molecule is a complementary copy of the template strand and thus a direct copy of the coding strand, except for the substitution of uracil for thymine.

Function

The primary function of the coding strand is to serve as a guide for the synthesis of mRNA during transcription. The sequence of nucleotides in the coding strand is used to determine the sequence of nucleotides in the mRNA, which in turn dictates the sequence of amino acids in a protein during the process of translation. This direct relationship between the sequence of the coding strand and the sequence of the protein is known as the central dogma of molecular biology.

Importance in Genetics

The coding strand plays a vital role in the study of genetics and molecular biology. By analyzing the sequence of the coding strand, scientists can predict the amino acid sequence of the protein encoded by a gene. Mutations in the coding strand can lead to changes in the protein product, which can have significant biological consequences, including the development of genetic disorders.

Comparison with Template Strand

While the coding strand and the template strand are both essential components of DNA, they serve different roles in the process of gene expression. The template strand is used as a template for RNA synthesis, meaning that the RNA polymerase reads this strand to create an RNA transcript. In contrast, the coding strand carries the genetic code that is ultimately translated into a protein, but it is not directly used by the RNA polymerase during transcription.

See Also

• Gene expression
• Transcription (genetics)
• Translation (biology)
• RNA polymerase
• Mutation
• Genetic disorder