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___________

Assuming the sequence shown is part of a eukaryotic gene, what consensus sequence(s) would you expect to identify within about 100 base pairs of the start of transcription?

Verified step by step guidance

1. Identify the transcription start site, which is the thymine nucleotide at the end of the given sequence.
2. Recognize that in eukaryotic genes, the core promoter region often contains specific consensus sequences.
3. Recall that the TATA box is a common consensus sequence found in the promoter region of eukaryotic genes, typically located about 25-35 base pairs upstream of the transcription start site.
4. Consider other potential consensus sequences such as the CAAT box or GC-rich regions, which may be found within 100 base pairs upstream of the transcription start site.
5. Diagram the location of these consensus sequences relative to the transcription start site, ensuring to note their approximate positions within the 100 base pair region.

Key Concepts

Transcription in Eukaryotes

Transcription in eukaryotes is the process by which RNA polymerase synthesizes RNA from a DNA template. This process occurs in the nucleus and involves several key steps: initiation, elongation, and termination. Eukaryotic transcription requires additional factors, such as transcription factors and enhancers, which help in the binding of RNA polymerase to the promoter region of the gene.

Consensus Sequences

Consensus sequences are short, recurring patterns in DNA that are crucial for the binding of proteins involved in transcription. These sequences, often found in promoter regions, are recognized by transcription factors and RNA polymerase, facilitating the initiation of transcription. Common consensus sequences in eukaryotes include the TATA box and the CAAT box, which are typically located upstream of the transcription start site.

Template and Nontemplate Strands

In DNA, the template strand is the strand that RNA polymerase reads to synthesize RNA, while the nontemplate strand, also known as the coding strand, has the same sequence as the RNA (except for thymine being replaced by uracil). Understanding the roles of these strands is essential for predicting the RNA sequence produced during transcription and for identifying consensus sequences that may be present in the nontemplate strand.