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 bacterial consensus sequence(s) in the approximate position(s) on the diagram.

Key Concepts

Transcription in Prokaryotes

Transcription in prokaryotes occurs in the cytoplasm and involves the synthesis of RNA from a DNA template. The process begins when RNA polymerase binds to the promoter region of the gene, which is recognized by consensus sequences. In bacteria, the most common consensus sequences are the -10 (Pribnow box) and -35 regions, which help initiate transcription.

Consensus Sequences

Consensus sequences are short, recurring patterns in DNA that are crucial for the binding of transcription factors and RNA polymerase. These sequences are typically found in the promoter region and are essential for the regulation of gene expression. In bacteria, the consensus sequences help determine the efficiency of transcription initiation.

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 produced (except for uracil replacing thymine). Understanding the roles of these strands is essential for predicting the RNA sequence and identifying the corresponding consensus sequences during transcription.