The accompanying illustration shows a portion of a gene undergoing transcription. The template and coding strands for the gene are labeled, and a segment of DNA sequence is given. For this gene segment:

Superimpose a drawing of RNA polymerase as it nears the end of transcription of the DNA sequence.

Key Concepts

Transcription

Transcription is the process by which the genetic information encoded in DNA is copied into messenger RNA (mRNA). During transcription, RNA polymerase binds to the DNA template strand and synthesizes a complementary RNA strand by adding ribonucleotides in the 5' to 3' direction. This process is crucial for gene expression, as it converts the genetic code into a format that can be translated into proteins.

RNA Polymerase

RNA polymerase is the enzyme responsible for synthesizing RNA from a DNA template during transcription. It unwinds the DNA double helix and catalyzes the formation of RNA by linking ribonucleotides together. Understanding the role of RNA polymerase is essential for visualizing its position and function during the transcription process, especially as it approaches the termination of transcription.

Coding and Template Strands

In the context of transcription, the coding strand of DNA has the same sequence as the resulting RNA (except for thymine being replaced by uracil), while the template strand is complementary to the RNA. The template strand serves as the actual guide for RNA polymerase, ensuring that the RNA sequence is accurately synthesized based on the genetic information. Recognizing the distinction between these strands is vital for understanding how RNA is produced from DNA.