The Direction of Transcription in DNA Strands

Question:

Is the polymerase transcribing CNCT2 into pre-mRNA moving to the left or to the right?

Question options:

The polymerase is moving to the right

The polymerase is moving to the left

The polymerase is not a part of transcription

Answer:

The polymerase is moving to the right. During transcription, the polymerase moves in the direction opposite to DNA replication. In this case, the polymerase is moving to the right along the template strand for the CNCT2 gene.

During transcription, DNA is unwound and RNA polymerase synthesizes a complementary RNA strand. In the given diagram, the gray boxes represent open reading frames, which are regions of DNA that encode proteins. The arrows indicate the direction of transcription for each gene.

In figure (b), we see a close-up of the DNA strands at a transcription bubble. The transcription bubble is formed when the DNA strands separate to allow RNA polymerase to access the template strand for transcription.

Since the gene labeled CNCT2 is in focus, we need to determine the direction in which the polymerase is moving during transcription. The direction of transcription is always from the 3' to the 5' end of the template strand, which is opposite to the direction of DNA replication.

By looking at the orientation of the arrow in figure (b), we can determine the direction of transcription. The arrow is pointing towards the right, indicating that the polymerase is moving to the right along the template strand. Therefore, the correct answer is that the polymerase is moving to the right.