Coding strand

Definition

In DNA, the strand whose 5′-to-3′ base sequence matches that of the transcribed RNA (with thymine replacing uracil). It carries the codons read during translation, while the complementary non-coding strand serves as the template for RNA polymerase. The distinction matters when annotating arthropod genomes, designing RNA-interference constructs, or mapping splice variants in insects and arachnids.

Etymology

From 'coding' (carrying the code for protein synthesis) + 'strand' (one chain of the DNA double helix)

Example

In the fruit fly Drosophila melanogaster, the coding strand of the white gene displays the same sequence as the mature mRNA (except T for U); researchers designing CRISPR guides must verify whether their oligos target the coding or template strand to ensure proper guide-RNA transcription.

Synonyms

• sense strand
• non-template strand

Related Terms

• template strand
• Transcription
• Codon
• Anticodon
• RNA polymerase
• complementary DNA
• genome annotation

Usage Notes

The term is relative to a specific transcription unit; the same DNA region can be coding for one gene and non-coding (template) for an overlapping gene on the opposite strand. In genome databases, the 'plus' or 'Watson' strand is often arbitrarily designated, so 'coding strand' should not be assumed synonymous with 'forward strand' without verification. Antonym: template strand (non-coding strand).