Elongation

Definition

Elongation refers to the stage in the process of transcription and translation where nucleic acids or polypeptides are extended by the addition of nucleotides or amino acids, respectively. This process is crucial for gene expression as it allows for the synthesis of RNA and proteins, ultimately determining the functionality of cells. During elongation, the molecular machinery works efficiently to add building blocks in a sequence that corresponds to the genetic code.

5 Must Know Facts For Your Next Test

1. During transcription elongation, RNA polymerase unwinds the DNA helix and adds complementary RNA nucleotides to the growing RNA strand.
2. Elongation continues until RNA polymerase reaches a termination signal, which signals the end of transcription.
3. In translation, elongation occurs when tRNAs bring amino acids to the ribosome, where they are added to the growing polypeptide chain based on the mRNA codon sequence.
4. The elongation factor proteins assist in both transcription and translation elongation, ensuring accuracy and efficiency in these processes.
5. The rate of elongation can be influenced by various factors, including the availability of substrates, enzyme activity, and cellular conditions.

Review Questions

• How does elongation differ between transcription and translation processes?
  • Elongation in transcription involves RNA polymerase synthesizing an RNA strand by adding nucleotides complementary to a DNA template. In contrast, elongation during translation occurs when ribosomes add amino acids to a growing polypeptide chain based on the sequence of codons in mRNA. While both processes involve extending a chain—nucleic acids for transcription and proteins for translation—their substrates and mechanisms are distinct.
• Discuss the role of elongation factors in enhancing the efficiency of transcription and translation.
  • Elongation factors are proteins that play a crucial role in both transcription and translation elongation. In transcription, they help stabilize the RNA polymerase complex and facilitate efficient nucleotide addition. During translation, elongation factors assist in delivering charged tRNA molecules to the ribosome, ensuring that amino acids are added correctly to the growing peptide chain. These factors enhance overall accuracy and speed, making them vital for proper gene expression.
• Evaluate how errors during elongation can impact gene expression and cellular functions.
  • Errors during elongation can lead to incorrect RNA or protein products, significantly affecting gene expression and cellular functions. For instance, if RNA polymerase incorporates incorrect nucleotides during transcription elongation, it can result in faulty mRNA that encodes dysfunctional proteins. Similarly, mistakes during translation can lead to polypeptides with wrong amino acid sequences, potentially disrupting cellular processes or causing diseases. Understanding these impacts emphasizes the importance of fidelity during the elongation phase.

Related terms

Transcription:

The process of synthesizing RNA from a DNA template, where the enzyme RNA polymerase reads the DNA and builds a complementary RNA strand.

Translation:

The process in which ribosomes synthesize proteins by translating the sequence of nucleotides in mRNA into a sequence of amino acids.

RNA Polymerase:

An enzyme that catalyzes the synthesis of RNA from a DNA template during transcription, playing a critical role in the elongation phase.