Elongation

Definition

Elongation is the process during protein synthesis where amino acids are added one by one to a growing polypeptide chain. This occurs in both transcription and translation, as RNA is synthesized from DNA and proteins are built from mRNA, respectively. Understanding elongation helps clarify how genetic information is translated into functional proteins and how the process is coordinated in prokaryotic and eukaryotic cells.

5 Must Know Facts For Your Next Test

1. During elongation in translation, tRNA molecules bring specific amino acids to the ribosome according to the codons present on the mRNA.
2. Elongation factors play a crucial role in ensuring the accuracy and efficiency of elongation by helping with the binding of tRNA and the translocation of the ribosome.
3. In eukaryotes, elongation involves multiple RNA polymerases, whereas prokaryotes use a single type of RNA polymerase for transcription.
4. Elongation can be terminated when a stop codon on the mRNA is reached, signaling that the polypeptide chain is complete.
5. The speed of elongation can vary greatly between prokaryotes and eukaryotes, with prokaryotic elongation generally occurring at a faster rate.

Review Questions

• How does elongation differ between transcription and translation?
  • Elongation in transcription involves RNA polymerase synthesizing RNA from a DNA template, adding nucleotides to form an RNA strand. In contrast, elongation in translation occurs when ribosomes decode mRNA to synthesize a polypeptide chain by linking amino acids brought in by tRNA. While both processes involve the addition of building blocks to a growing chain, the types of building blocks and the mechanisms differ significantly.
• What role do elongation factors play during protein synthesis, and why are they important?
  • Elongation factors are essential proteins that assist during the elongation phase of protein synthesis. They help ensure that tRNAs correctly bind to the ribosome in response to mRNA codons and facilitate the movement of the ribosome along the mRNA strand. By promoting accurate tRNA loading and ribosomal translocation, elongation factors enhance the efficiency and fidelity of protein synthesis.
• Analyze how errors during elongation can affect protein synthesis and cellular function.
  • Errors during elongation can lead to the incorporation of incorrect amino acids into a polypeptide chain, resulting in misfolded or nonfunctional proteins. Such mistakes can disrupt cellular functions and lead to diseases or malfunctions at the cellular level. For example, if an essential enzyme is improperly synthesized due to elongation errors, it could impair metabolic pathways, leading to significant consequences for organismal health and development.

Related terms

Transcription: The process by which RNA polymerase synthesizes RNA from a DNA template.

Translation:

The process where ribosomes decode mRNA to assemble amino acids into a polypeptide chain.

Ribosome: The cellular machinery that facilitates the translation of mRNA into proteins by catalyzing peptide bond formation between amino acids.