Describe the two types of transcription termination found in bacterial genes. How does transcription termination differ for eukaryotic genes?
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 16c
Textbook Question
The segment of the bacterial TrpA gene involved in intrinsic termination of transcription is the following:
3'-TGGGTCGGGGCGGATTACTGCCCCGAAAAAAAACTTG-5'
5'-ACCCAGCCCCGCCTAATGACGGGGCTTTTTTTTGAAC-3'
Explain how a sequence of this type leads to intrinsic termination of transcription.

1
Intrinsic termination of transcription in bacteria relies on specific sequences in the DNA that form a hairpin structure in the RNA transcript. Begin by identifying the sequence in the given DNA that could form a complementary base-pairing region in the RNA transcript.
Look for a region in the DNA sequence that is rich in G and C nucleotides. These regions are important because they form strong hydrogen bonds, leading to the formation of a stable hairpin structure in the RNA transcript.
After the GC-rich region, identify the stretch of adenine (A) nucleotides on the template strand (3'-5' strand). This corresponds to a stretch of uracil (U) nucleotides in the RNA transcript, which forms a weak RNA-DNA hybrid due to the weaker A-U base pairing.
Explain that during transcription, the RNA polymerase transcribes the GC-rich region, which folds into a hairpin structure in the RNA. This structure causes the RNA polymerase to pause.
Finally, describe how the weak A-U base pairing downstream of the hairpin destabilizes the RNA-DNA hybrid, leading to the release of the RNA transcript and termination of transcription.

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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Intrinsic Termination of Transcription
Intrinsic termination is a mechanism by which RNA polymerase stops transcription without the need for additional factors. It typically involves the formation of a stable hairpin structure in the RNA transcript, followed by a stretch of uracil residues. This hairpin structure disrupts the interaction between the RNA polymerase and the DNA template, leading to the release of the newly synthesized RNA.
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Hairpin Structure Formation
The hairpin structure is formed when complementary sequences within the RNA transcript base-pair with each other, creating a double-stranded region. This structure is crucial for intrinsic termination as it stabilizes the RNA molecule and causes RNA polymerase to pause. The presence of a GC-rich region followed by a series of uracils is often indicative of potential hairpin formation, which is essential for signaling the end of transcription.
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Role of Uracil in Termination
Uracil plays a significant role in the intrinsic termination process due to its weaker base-pairing with adenine compared to guanine-cytosine pairs. After the formation of the hairpin, the RNA polymerase encounters a stretch of uracils, which destabilizes the RNA-DNA hybrid. This instability leads to the dissociation of the RNA transcript from the DNA template, effectively terminating transcription.
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