Intrinsic termination is a mechanism that causes the end of transcription in prokaryotes, relying on specific sequences in the DNA template. This process occurs when the RNA polymerase transcribes a region of DNA that forms a hairpin loop structure in the RNA, followed by a series of uracil nucleotides. The formation of this hairpin disrupts the interaction between RNA polymerase and the RNA transcript, leading to the release of the newly synthesized RNA molecule.
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Intrinsic termination relies on the presence of specific sequences in the newly synthesized RNA that can fold into a stable hairpin structure.
The sequence following the hairpin is typically rich in uracil, which weakens the hydrogen bonds between the RNA and DNA, facilitating termination.
This process is efficient and does not require any additional proteins or factors, making it a simpler form of termination compared to Rho-dependent termination.
Intrinsic termination is crucial for ensuring proper gene expression and preventing unnecessary transcription of adjacent genes.
The stability of the hairpin structure is essential; if it fails to form or is unstable, transcription may continue past the intended termination site.
Review Questions
What is the role of the hairpin structure in intrinsic termination and how does it affect RNA polymerase?
The hairpin structure plays a critical role in intrinsic termination by causing RNA polymerase to stall during transcription. When the RNA forms this stable hairpin, it disrupts the interaction between the enzyme and the RNA transcript. This disruption leads to the release of the RNA molecule from RNA polymerase, effectively ending transcription without requiring additional factors.
Compare intrinsic termination with Rho-dependent termination in terms of mechanisms and requirements.
Intrinsic termination is a simpler process that occurs without any external factors, relying solely on specific sequences within the RNA to form a hairpin loop and destabilize the interaction with RNA polymerase. In contrast, Rho-dependent termination requires the Rho protein to bind to the RNA and facilitate dissociation of RNA polymerase from the DNA template. Thus, while intrinsic termination uses inherent features of RNA sequences for termination, Rho-dependent relies on additional protein interactions.
Evaluate how intrinsic termination contributes to gene regulation in prokaryotic cells and its implications for overall cellular function.
Intrinsic termination contributes significantly to gene regulation by ensuring that transcription stops at appropriate locations, thus preventing unnecessary production of proteins that may interfere with cellular processes. By effectively managing when and how much mRNA is produced, intrinsic termination allows prokaryotic cells to quickly adapt to environmental changes and regulate metabolic pathways efficiently. This precise control over gene expression ultimately supports overall cellular function and survival in varying conditions.
Related terms
RNA polymerase: An enzyme responsible for synthesizing RNA from a DNA template during transcription.
Rho factor: A protein involved in the Rho-dependent termination of transcription in prokaryotes, which requires additional factors compared to intrinsic termination.
Promoter: A specific DNA sequence where RNA polymerase binds to initiate transcription.