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, draw the approximate positions of the promoter sequence and the termination sequence.

Verified step by step guidance

1. Understand the structure of the DNA strands: The nontemplate strand (also called the coding strand) has the same sequence as the RNA transcript (except thymine is replaced with uracil in RNA). The template strand is complementary to the RNA transcript and is used by RNA polymerase during transcription.
2. Identify the transcription start site: The problem states that transcription starts at the thymine nucleotide at the end of the sequence. This means the RNA polymerase will begin synthesizing RNA from the complementary adenine on the template strand.
3. Locate the promoter sequence: In bacterial genes, the promoter is typically located upstream of the transcription start site. The -10 region (Pribnow box) often has the consensus sequence TATAAT, and the -35 region has the consensus sequence TTGACA. Approximate their positions relative to the transcription start site on the nontemplate strand.
4. Determine the termination sequence: In bacteria, termination sequences can be rho-dependent or rho-independent. Rho-independent termination often involves a GC-rich region followed by a series of uracils in the RNA transcript. Look for a potential GC-rich region and a poly-T sequence on the template strand, as these would correspond to the termination signal.
5. Diagram the positions: On the nontemplate strand, mark the approximate locations of the promoter (-10 and -35 regions) upstream of the transcription start site and the termination sequence downstream of the transcribed region. Ensure the diagram reflects the bacterial gene structure.

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 at a promoter region, where RNA polymerase binds to initiate transcription. In bacteria, the promoter is typically located upstream of the gene, and transcription continues until a termination signal is reached, resulting in the production of a messenger RNA (mRNA) molecule.

Promoter and Terminator Sequences

Promoter sequences are specific DNA regions that signal the start of transcription, usually containing consensus sequences recognized by RNA polymerase. In contrast, terminator sequences signal the end of transcription, causing RNA polymerase to detach from the DNA. Understanding the locations of these sequences is crucial for mapping the transcriptional unit of a gene.

Nontemplate and Template Strands

In DNA, the nontemplate strand (also known as the coding strand) has the same sequence as the RNA transcript (except for thymine being replaced by uracil), while the template strand is complementary to the RNA. During transcription, RNA polymerase reads the template strand to synthesize RNA, making it essential to identify both strands when analyzing gene expression and transcriptional processes.