Elongation

Definition

Elongation is a critical phase in protein synthesis, specifically during the translation process, where the polypeptide chain is formed by sequentially adding amino acids. This phase occurs after initiation and involves the ribosome moving along the mRNA strand, facilitating the binding of tRNA molecules carrying specific amino acids. The elongation phase is essential for building the protein's primary structure, ultimately determining its function and activity in the cell.

5 Must Know Facts For Your Next Test

1. During elongation, the ribosome translocates along the mRNA, moving three nucleotides at a time, which corresponds to one codon.
2. Elongation factors assist in the process by promoting the binding of tRNA and helping to ensure accurate amino acid incorporation.
3. The peptide bond formation between amino acids during elongation is catalyzed by the ribosomal RNA within the ribosome's active site.
4. This phase can be characterized by three main steps: aminoacyl-tRNA binding, peptide bond formation, and translocation.
5. Elongation continues until a stop codon is encountered on the mRNA, signaling the termination of protein synthesis.

Review Questions

• How does elongation contribute to the overall process of protein synthesis?
  • Elongation is crucial in protein synthesis as it directly involves the addition of amino acids to the growing polypeptide chain. This phase allows for the ribosome to move along the mRNA sequence, translating each codon into its corresponding amino acid. The accuracy and efficiency of elongation affect the final protein's structure and function, making it an essential component of translation.
• What roles do elongation factors play during the elongation phase of translation?
  • Elongation factors are essential proteins that facilitate various steps during elongation. They assist in the proper binding of aminoacyl-tRNA to the ribosome and help in stabilizing the interactions between tRNA and mRNA. By promoting efficient translocation of the ribosome along the mRNA, elongation factors ensure that translation proceeds smoothly and accurately, thereby enhancing protein synthesis.
• Evaluate how errors during elongation could impact protein function and cellular activities.
  • Errors during elongation can lead to incorrect amino acid incorporation into proteins, potentially resulting in dysfunctional or misfolded proteins. Such mistakes can disrupt normal cellular activities, leading to diseases or malfunctions within biological systems. In some cases, faulty proteins may interfere with crucial processes such as enzymatic reactions or signaling pathways, emphasizing the importance of accuracy during this phase of translation.

Related terms

Translation: The process in which ribosomes synthesize proteins by decoding mRNA sequences into polypeptide chains.

tRNA (transfer RNA): A type of RNA molecule that carries amino acids to the ribosome during protein synthesis, matching them to the coded mRNA sequence.

Ribosome: The cellular machinery that facilitates the translation of mRNA into proteins, composed of rRNA and proteins.