Elongation

Definition

Elongation refers to the process during which nucleotides are added to a growing DNA or RNA strand. This phase is crucial in both DNA replication and protein synthesis, as it determines the length of the new strand being formed. During elongation, enzymes such as DNA polymerases and RNA polymerases play essential roles in facilitating the addition of complementary bases, ensuring that genetic information is accurately copied and translated into functional proteins.

5 Must Know Facts For Your Next Test

1. During DNA replication, elongation occurs after the initiation phase, where RNA primers are laid down to start the synthesis of new DNA strands.
2. In transcription, elongation involves the addition of ribonucleotides to form an RNA molecule that is complementary to the DNA template strand.
3. The speed of elongation can vary significantly; for example, DNA replication occurs at approximately 50 nucleotides per second in human cells.
4. Elongation is highly accurate due to proofreading mechanisms employed by DNA and RNA polymerases, which help correct errors in nucleotide incorporation.
5. In translation, elongation involves the sequential addition of amino acids to the growing polypeptide chain as tRNA molecules deliver the correct amino acids based on mRNA codons.

Review Questions

• How does elongation differ between DNA replication and protein synthesis?
  • Elongation in DNA replication involves the addition of nucleotides to form a new DNA strand using DNA polymerase, while elongation in protein synthesis entails adding amino acids to a growing polypeptide chain using transfer RNA (tRNA) and ribosomes. In DNA replication, this process ensures that genetic information is accurately copied for cell division. In contrast, during protein synthesis, elongation allows for the translation of mRNA sequences into functional proteins, crucial for cellular functions.
• What are the roles of enzymes during the elongation phase in both DNA replication and transcription?
  • In DNA replication, DNA polymerase plays a vital role during elongation by adding nucleotides to the growing strand while proofreading for errors. In transcription, RNA polymerase takes over, synthesizing RNA by adding ribonucleotides complementary to the template strand of DNA. Both enzymes ensure accuracy and efficiency in their respective processes, maintaining genetic fidelity and proper gene expression.
• Evaluate how errors during elongation can impact cellular function and organismal health.
  • Errors during elongation can lead to mutations in DNA or incorrect protein synthesis, which may have significant consequences for cellular function and overall organismal health. Mutations can result in dysfunctional proteins that impair metabolic pathways or disrupt cell signaling processes. In severe cases, such mutations can contribute to diseases like cancer or genetic disorders. Thus, accurate elongation processes are crucial for maintaining genetic integrity and ensuring proper biological function across all levels of life.

Related terms

DNA Polymerase: An enzyme responsible for synthesizing new strands of DNA by adding nucleotides complementary to the template strand during replication.

RNA Polymerase: An enzyme that catalyzes the synthesis of RNA from a DNA template during transcription, playing a critical role in gene expression.

Peptide Bond: The covalent bond formed between amino acids during protein synthesis, linking them together in a growing polypeptide chain.