Wild-type E. coli grow best at 37°C but can grow efficiently up to 42°C. An E. coli strain has a mutation of the sigma subunit that results in an RNA polymerase holoenzyme that is stable and transcribes at wild-type levels at 37°C. The mutant holoenzyme is progressively destabilized as the temperature is raised, and it completely denatures and ceases to carry out transcription at 42°C. Relative to wild-type growth, characterize the ability of the mutant strain to carry out transcription at 37°C
Table of contents
- 1. Introduction to Genetics51m
- 2. Mendel's Laws of Inheritance3h 37m
- 3. Extensions to Mendelian Inheritance2h 41m
- 4. Genetic Mapping and Linkage2h 28m
- 5. Genetics of Bacteria and Viruses1h 21m
- 6. Chromosomal Variation1h 48m
- 7. DNA and Chromosome Structure56m
- 8. DNA Replication1h 10m
- 9. Mitosis and Meiosis1h 34m
- 10. Transcription1h 0m
- 11. Translation58m
- 12. Gene Regulation in Prokaryotes1h 19m
- 13. Gene Regulation in Eukaryotes44m
- 14. Genetic Control of Development44m
- 15. Genomes and Genomics1h 50m
- 16. Transposable Elements47m
- 17. Mutation, Repair, and Recombination1h 6m
- 18. Molecular Genetic Tools19m
- 19. Cancer Genetics29m
- 20. Quantitative Genetics1h 26m
- 21. Population Genetics50m
- 22. Evolutionary Genetics29m
10. Transcription
Transcription in Prokaryotes
Problem 29e
Textbook Question
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.

1
Identify the transcription start site, which is the thymine nucleotide at the end of the sequence provided. This will help you orient the sequence and determine the upstream and downstream regions.
Understand that bacterial promoters typically contain two conserved regions: the -10 region (Pribnow box) and the -35 region. These regions are located upstream of the transcription start site and are critical for RNA polymerase binding.
Determine the approximate positions of the -10 and -35 regions relative to the transcription start site. The -10 region is approximately 10 base pairs upstream, and the -35 region is approximately 35 base pairs upstream of the transcription start site.
Write the bacterial consensus sequences for the -10 and -35 regions. The -10 consensus sequence is typically 'TATAAT', and the -35 consensus sequence is typically 'TTGACA'. These sequences may vary slightly depending on the specific bacterial species.
Place the consensus sequences in the appropriate positions on the nontemplate strand of the DNA diagram. The -10 sequence should be approximately 10 base pairs upstream of the transcription start site, and the -35 sequence should be approximately 35 base pairs upstream.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
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 a gene, unwinding the DNA strands. The nontemplate strand serves as the coding strand, while the template strand is used to synthesize the complementary RNA. Understanding this process is crucial for identifying consensus sequences that guide RNA polymerase binding.
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Prokaryotic Transcription
Consensus Sequences
Consensus sequences are short, recurring patterns in DNA that are crucial for the binding of transcription factors and RNA polymerase. In prokaryotes, the most well-known consensus sequences are the -10 (Pribnow box) and -35 regions, which are located upstream of the transcription start site. These sequences help ensure the efficient initiation of transcription by providing a recognizable site for the transcription machinery.
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Sequencing Overview
Template and Nontemplate Strands
In the context of DNA transcription, the template strand is the DNA strand that is read by RNA polymerase to synthesize RNA, while the nontemplate strand, also known as the coding strand, has the same sequence as the RNA produced (except for thymine being replaced by uracil). Understanding the roles of these strands is essential for accurately determining the RNA sequence and identifying the corresponding consensus sequences in the given DNA.
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Double Strand Breaks
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