The DNA sequence below gives the first 12 base pairs of the transcribed region of a gene, and the template and nontemplate strands of DNA are identified. The transcription start is the thymine nucleotide at the end of the sequence given. Use the diagram to answer the list of questions. Make a copy of the diagram before you begin answering the questions, or have one group member diagram the answers for bacteria and another group member diagram the answers for eukaryotes.
Nontemplate strand ___________ TTGCTACGGTCA___________
Template strand    ___________ AACGATGCCAGT___________
Write the anticipated eukaryotic consensus sequence(s) in the approximate position(s) on the diagram.

Verified step by step guidance

1. Identify the transcription start site in the given DNA sequence. The problem states that the transcription starts at the thymine nucleotide at the end of the sequence provided. This will help you orient the sequence for further analysis.
2. Determine the direction of transcription. Transcription proceeds in the 5' to 3' direction of the RNA strand, which corresponds to the 3' to 5' direction of the template strand. This means the RNA polymerase will read the template strand (AACGATGCCAGT) from 3' to 5'.
3. Locate the approximate positions of the eukaryotic consensus sequences. In eukaryotes, the most common consensus sequences are the TATA box (TATAAA) located approximately 25-30 base pairs upstream of the transcription start site and the CAAT box (GGCCAATCT) located approximately 75-80 base pairs upstream.
4. Mark the positions of the TATA box and CAAT box on the nontemplate strand. Since the nontemplate strand is complementary to the template strand, you will need to count upstream from the transcription start site (thymine) to place these sequences in their approximate positions.
5. Diagram the anticipated eukaryotic consensus sequences on the nontemplate strand. For example, place the TATA box approximately 25-30 base pairs upstream and the CAAT box approximately 75-80 base pairs upstream, ensuring the sequences are written in the 5' to 3' direction of the nontemplate strand.

Key Concepts

Transcription

Transcription is the process by which the genetic information encoded in DNA is copied into messenger RNA (mRNA). This occurs in the nucleus of eukaryotic cells, where RNA polymerase binds to the template strand of DNA and synthesizes a complementary RNA strand. Understanding transcription is crucial for analyzing gene expression and the role of various sequences in regulating this process.

Consensus Sequence

A consensus sequence is a sequence of DNA that is highly conserved across different genes and species, indicating its importance in biological functions. In the context of transcription, consensus sequences often represent binding sites for transcription factors and RNA polymerase, which are essential for initiating transcription. Identifying these sequences helps in understanding gene regulation and expression patterns.

Eukaryotic Gene Structure

Eukaryotic genes typically consist of exons (coding regions) and introns (non-coding regions), with regulatory elements such as promoters and enhancers. The transcription process in eukaryotes involves additional complexities, including the need for RNA processing (capping, polyadenylation, and splicing) before the mRNA is translated into protein. Familiarity with eukaryotic gene structure is vital for accurately predicting transcription outcomes and understanding gene regulation.