Terminator

Definition

In the context of protein synthesis, the terminator is a sequence of nucleotides in the messenger RNA (mRNA) that signals the end of the coding region and the completion of translation. The terminator triggers the release of the newly synthesized polypeptide chain from the ribosome, allowing the mRNA and ribosomal subunits to dissociate and be recycled for future rounds of protein synthesis. The terminator is a crucial component in the process of protein synthesis, ensuring that the translation machinery accurately produces the intended protein product and then disassembles to prepare for the next round of translation.

5 Must Know Facts For Your Next Test

1. The terminator sequence in mRNA is typically composed of a GC-rich stem-loop structure followed by a run of uracil (U) residues.
2. The terminator signal is recognized by release factors in the ribosome, which trigger the dissociation of the ribosomal subunits and the release of the newly synthesized polypeptide chain.
3. Proper termination of translation is essential for ensuring the accuracy and efficiency of protein synthesis, as it prevents the production of incomplete or incorrect protein products.
4. Mutations or disruptions in the terminator sequence can lead to read-through translation, where the ribosome continues synthesizing the polypeptide chain beyond the intended stop codon, resulting in potentially non-functional or harmful proteins.
5. The terminator sequence is a key regulatory element in gene expression, as it can influence the stability and processing of the mRNA transcript, as well as the efficiency of translation.

Review Questions

• Describe the role of the terminator sequence in the process of protein synthesis.
  • The terminator sequence in mRNA plays a crucial role in the completion of translation by signaling the end of the coding region and triggering the release of the newly synthesized polypeptide chain from the ribosome. This sequence, typically composed of a GC-rich stem-loop structure followed by a run of uracil (U) residues, is recognized by release factors in the ribosome, which then dissociate the ribosomal subunits and allow the mRNA and ribosomal components to be recycled for future rounds of protein synthesis. Proper termination is essential for ensuring the accuracy and efficiency of protein production, as it prevents the synthesis of incomplete or incorrect protein products.
• Explain how mutations or disruptions in the terminator sequence can impact the process of protein synthesis.
  • Mutations or disruptions in the terminator sequence can lead to read-through translation, where the ribosome continues synthesizing the polypeptide chain beyond the intended stop codon. This can result in the production of potentially non-functional or harmful proteins, as the extended polypeptide chain may fold incorrectly or include additional amino acids that are not part of the intended protein product. Disruptions in the terminator sequence can also influence the stability and processing of the mRNA transcript, as well as the overall efficiency of translation, further impacting the accuracy and quality of the final protein synthesized.
• Analyze the significance of the terminator sequence as a regulatory element in gene expression.
  • The terminator sequence is a key regulatory element in gene expression, as it can influence multiple aspects of the protein synthesis process. Beyond its role in signaling the end of translation and triggering the release of the polypeptide chain, the terminator sequence can also affect the stability and processing of the mRNA transcript. This, in turn, can impact the efficiency of translation and the overall expression levels of the gene. Additionally, the terminator sequence serves as a checkpoint in the gene expression pathway, ensuring the accuracy and fidelity of protein synthesis by preventing the production of incomplete or incorrect protein products. By understanding the regulatory functions of the terminator sequence, researchers can gain valuable insights into the complex mechanisms that govern gene expression and protein homeostasis within cells.

Related terms

Transcription:

The process of synthesizing a complementary RNA molecule (mRNA) from a DNA template, which is the first step in gene expression.

Translation:

The process of synthesizing a polypeptide chain from the information encoded in the mRNA, which is the second step in gene expression.

Ribosome:

The cellular organelle responsible for the synthesis of proteins, composed of rRNA and proteins, which serves as the site of translation.