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 bacterial gene, what consensus sequence(s) would you expect to identify in the promoter?

Key Concepts

Promoter Regions

Promoter regions are specific sequences of DNA located upstream of a gene that serve as binding sites for RNA polymerase and transcription factors. In bacteria, common consensus sequences found in promoters include the -10 (Pribnow box) and -35 regions, which are crucial for the initiation of transcription. Understanding these sequences helps in predicting where transcription will begin and how efficiently a gene will be expressed.

Transcription in Bacteria

Transcription in bacteria is the process by which RNA is synthesized from a DNA template. It involves the binding of RNA polymerase to the promoter region, followed by the unwinding of DNA and the synthesis of a complementary RNA strand. This process is essential for gene expression and is regulated by various factors, including the presence of specific consensus sequences in the promoter.

Consensus Sequences

Consensus sequences are short, recurring patterns in DNA that are recognized by proteins involved in transcription, such as RNA polymerase. These sequences represent the most common nucleotides found at specific positions in a set of related sequences and are critical for the binding of transcription machinery. Identifying these sequences in a promoter can provide insights into the regulation and efficiency of gene transcription.