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:

Indicate the direction in which RNA polymerase moves as it transcribes this gene.

Key Concepts

Transcription Process

Transcription is the process by which RNA polymerase synthesizes RNA from a DNA template. During this process, the enzyme reads the DNA sequence of the gene and constructs a complementary RNA strand. This occurs in the nucleus of eukaryotic cells and is the first step in gene expression, leading to the production of proteins.

Directionality of RNA Synthesis

RNA polymerase synthesizes RNA in a 5' to 3' direction, meaning it adds nucleotides to the 3' end of the growing RNA strand. This directionality is crucial for maintaining the correct sequence of nucleotides and ensuring that the RNA molecule is complementary to the DNA template strand, which is read in the 3' to 5' direction.

Template and Coding Strands

In a gene, the template strand is the DNA strand that RNA polymerase uses to synthesize RNA, while the coding strand has the same sequence as the RNA (except for thymine being replaced by uracil). Understanding which strand serves as the template is essential for determining the direction of transcription and the resulting RNA sequence.