Transcription termination

Definition

Transcription termination is the process by which RNA synthesis is concluded, signaling the end of transcription in eukaryotic cells. This crucial step ensures that RNA polymerase disengages from the DNA template and releases the newly synthesized RNA molecule. The mechanisms that govern transcription termination in eukaryotes involve various factors and sequences that help regulate gene expression, linking this process to broader gene regulation mechanisms.

5 Must Know Facts For Your Next Test

1. In eukaryotes, transcription termination typically involves specific sequences in the DNA known as terminators, which signal RNA polymerase to stop transcription.
2. The process of transcription termination can occur through two main mechanisms: factor-dependent termination and factor-independent termination.
3. After transcription termination, RNA undergoes several processing steps, including capping, splicing, and polyadenylation, before becoming mature mRNA.
4. Transcription termination is crucial for proper gene expression as it prevents the unnecessary synthesis of RNA and allows for the regulation of gene products.
5. Faulty transcription termination can lead to issues such as incomplete RNA transcripts or extended transcription, potentially resulting in nonfunctional proteins.

Review Questions

• How does transcription termination ensure the fidelity of gene expression in eukaryotic cells?
  • Transcription termination plays a vital role in ensuring that RNA polymerase stops synthesizing RNA at the correct location, which helps maintain the integrity of gene expression. By accurately recognizing terminator sequences, RNA polymerase releases the newly formed RNA molecule without producing extraneous or incomplete transcripts. This precise regulation is essential for producing functional proteins and controlling overall gene expression within the cell.
• Discuss the differences between factor-dependent and factor-independent transcription termination mechanisms in eukaryotes.
  • Factor-dependent termination requires specific proteins that bind to DNA sequences and influence RNA polymerase's ability to dissociate from the template. In contrast, factor-independent termination relies on intrinsic properties of the RNA molecule itself, such as the formation of a hairpin loop followed by a poly-U tract that destabilizes the RNA-DNA hybrid. Understanding these differences provides insight into how various regulatory mechanisms can affect gene expression at the level of transcription.
• Evaluate the consequences of mutations in terminator sequences on eukaryotic gene regulation and expression.
  • Mutations in terminator sequences can lead to significant disruptions in gene regulation and expression. If a terminator sequence is altered or lost, RNA polymerase may fail to terminate transcription properly, resulting in either incomplete or overly extended RNA products. Such aberrant transcripts can affect downstream processes like splicing and translation, ultimately producing dysfunctional proteins that can disrupt cellular functions and contribute to disease states.

Related terms

RNA polymerase: An enzyme responsible for synthesizing RNA from a DNA template during transcription.

polyadenylation: The addition of a poly(A) tail to the 3' end of mRNA, which plays a significant role in mRNA stability and transport.

transcription factors: Proteins that bind to specific DNA sequences to regulate the transcription of genes by assisting or blocking the binding of RNA polymerase.