Termination Sequence

Definition

The termination sequence is a specific DNA sequence that signals the end of transcription, causing the RNA polymerase enzyme to detach from the DNA template and release the newly synthesized RNA molecule. It is a critical component of the transcription process, ensuring the proper termination of gene expression.

5 Must Know Facts For Your Next Test

1. The termination sequence is typically composed of a GC-rich palindromic sequence followed by a run of uridine (U) residues in the nascent RNA molecule.
2. The termination sequence acts as a signal for the RNA polymerase to release the newly synthesized RNA and dissociate from the DNA template.
3. Proper termination of transcription is essential for the regulation of gene expression, as it prevents the continuous production of unwanted RNA molecules.
4. Rho-dependent termination is a common mechanism in bacteria, where the Rho protein binds to the nascent RNA and causes the RNA polymerase to terminate transcription.
5. Eukaryotic cells, such as those found in higher organisms, often use a different mechanism called poly(A) signal-dependent termination, which involves the addition of a poly(A) tail to the 3' end of the RNA molecule.

Review Questions

• Explain the role of the termination sequence in the transcription process.
  • The termination sequence is a critical component of the transcription process, as it signals the RNA polymerase enzyme to release the newly synthesized RNA molecule and dissociate from the DNA template. This sequence, typically composed of a GC-rich palindromic region followed by a run of uridine residues, acts as a signal for the RNA polymerase to terminate transcription and ensure the proper regulation of gene expression. Without the termination sequence, the RNA polymerase would continue transcribing indefinitely, leading to the production of unwanted RNA molecules.
• Describe the differences between rho-dependent and poly(A) signal-dependent termination mechanisms.
  • Rho-dependent termination is a common mechanism in bacteria, where the Rho protein binds to the nascent RNA and causes the RNA polymerase to terminate transcription. In contrast, eukaryotic cells, such as those found in higher organisms, often use a different mechanism called poly(A) signal-dependent termination. This mechanism involves the addition of a poly(A) tail to the 3' end of the RNA molecule, which signals the RNA polymerase to release the transcript and dissociate from the DNA template. The specific termination mechanism used can have important implications for the regulation of gene expression in different organisms.
• Analyze the significance of proper termination of transcription for the regulation of gene expression.
  • The proper termination of transcription is essential for the regulation of gene expression, as it prevents the continuous production of unwanted RNA molecules. If the termination sequence is not recognized or the termination process is disrupted, the RNA polymerase may continue transcribing indefinitely, leading to the accumulation of unnecessary RNA transcripts. This could result in the overproduction of certain proteins or the expression of genes that should be silenced, ultimately disrupting the delicate balance of cellular processes. Consequently, the termination sequence and the mechanisms that ensure its proper recognition play a crucial role in maintaining the appropriate regulation of gene expression within the cell.

Related terms

Transcription:

The process of copying the genetic information stored in DNA into a complementary RNA molecule, which can then be used as a template for protein synthesis.

RNA Polymerase:

The enzyme responsible for catalyzing the synthesis of RNA from a DNA template during the process of transcription.

Rho-Dependent Termination: A mechanism of transcription termination in which the Rho protein binds to the nascent RNA and causes the RNA polymerase to detach from the DNA template.