Elongation

Definition

Elongation is a critical phase of protein synthesis during which amino acids are sequentially added to a growing polypeptide chain. This process occurs after the initiation phase and continues until a stop codon is reached on the mRNA. The elongation phase is vital for building proteins, as it involves the ribosome moving along the mRNA and facilitating the formation of peptide bonds between amino acids.

5 Must Know Facts For Your Next Test

1. During elongation, the ribosome translocates along the mRNA, moving from one codon to the next, allowing for the addition of new amino acids.
2. The process requires energy in the form of GTP, which is hydrolyzed to provide the necessary energy for tRNA binding and ribosomal movement.
3. Elongation factors play a crucial role in assisting with the binding of tRNA to the ribosome and ensuring accuracy during protein synthesis.
4. The elongation phase continues until a stop codon is reached, signaling the termination of protein synthesis.
5. Each amino acid is added in a specific sequence dictated by the codons in the mRNA, ensuring that proteins are synthesized accurately according to genetic information.

Review Questions

• How does elongation contribute to the overall process of protein synthesis?
  • Elongation is essential in protein synthesis as it involves the sequential addition of amino acids to form a polypeptide chain. The ribosome moves along the mRNA, translating its sequence into an ordered string of amino acids based on codon recognition. This phase ensures that proteins are accurately synthesized according to genetic instructions, ultimately determining their structure and function.
• Discuss the role of elongation factors during the elongation phase of protein synthesis.
  • Elongation factors are crucial proteins that facilitate various steps during elongation. They help in binding tRNA to the ribosome, ensuring that each tRNA brings the correct amino acid as specified by the codon on the mRNA. Additionally, these factors assist in ribosomal translocation, allowing the ribosome to move smoothly along the mRNA strand and maintaining the efficiency and accuracy of protein synthesis.
• Evaluate how errors during elongation might impact protein function and cellular processes.
  • Errors during elongation can lead to incorrect amino acid incorporation into proteins, potentially resulting in malfunctioning or non-functional proteins. This can disrupt cellular processes, as proteins play critical roles in enzymatic reactions, structural integrity, and cellular communication. Such mistakes can contribute to diseases or malfunctions at a cellular level, highlighting how tightly regulated elongation must be for proper cellular function.

Related terms

Peptide Bond: A chemical bond formed between two amino acids during protein synthesis, linking the carboxyl group of one amino acid to the amino group of another.

Ribosome: A molecular machine that facilitates the translation of mRNA into a polypeptide chain, composed of ribosomal RNA and proteins.

tRNA (Transfer RNA): Molecules that transport specific amino acids to the ribosome during protein synthesis, matching them to the corresponding codons on the mRNA.