key term - Transcription elongation

Definition

Transcription elongation is the process during gene expression where RNA polymerase synthesizes a strand of RNA from a DNA template, extending the RNA molecule by adding ribonucleotides one by one. This phase occurs after the initiation of transcription and is crucial for creating a complete RNA transcript that carries the genetic information required for protein synthesis. During this phase, RNA polymerase moves along the DNA, unwinding the double helix and synthesizing RNA in the 5' to 3' direction.

5 Must Know Facts For Your Next Test

1. Transcription elongation involves the addition of ribonucleotides to the growing RNA chain, facilitated by the active site of RNA polymerase.
2. During elongation, RNA polymerase must unwind the DNA double helix ahead of itself while rewinding it behind as it moves along.
3. Various transcription factors assist in regulating the speed and efficiency of elongation, ensuring proper gene expression.
4. Elongation can be influenced by several factors such as DNA sequence elements and modifications to RNA polymerase itself.
5. Errors made during elongation can be corrected through a process known as transcription-coupled repair, which enhances the fidelity of RNA synthesis.

Review Questions

• What role does RNA polymerase play during transcription elongation, and how does its function relate to the overall process of gene expression?
  • RNA polymerase is the central enzyme in transcription elongation, responsible for synthesizing RNA by adding ribonucleotides to the growing RNA strand. Its function is essential for gene expression as it transcribes genetic information from DNA into RNA, which is then translated into proteins. The activity of RNA polymerase not only affects the rate of elongation but also influences how genes are regulated during this critical phase of gene expression.
• How do transcription factors impact the process of transcription elongation, and what mechanisms do they use to regulate this phase?
  • Transcription factors play a vital role in regulating transcription elongation by influencing both the activity of RNA polymerase and the structure of chromatin. They can enhance or inhibit elongation by binding to specific DNA sequences near genes or interacting with RNA polymerase directly. Some transcription factors are involved in modifying chromatin structure, making it more accessible for elongation to occur, while others may slow down or pause elongation in response to cellular signals.
• Evaluate how transcription elongation errors can affect cellular function and what mechanisms exist to ensure accuracy during this process.
  • Errors that occur during transcription elongation can lead to faulty RNA molecules, which may result in the production of nonfunctional or harmful proteins. This can disrupt cellular functions and contribute to disease states. To mitigate these errors, cells employ mechanisms such as transcription-coupled repair that identify and rectify mistakes during synthesis. Additionally, proofreading activities associated with RNA polymerase help maintain fidelity, ensuring that most transcripts are accurate and functional.

Related terms

RNA polymerase:

An enzyme responsible for synthesizing RNA from a DNA template during transcription, playing a key role in both initiation and elongation phases.

promoter:

A specific region of DNA where transcription begins, allowing RNA polymerase to bind and initiate the transcription process.

termination:

The final phase of transcription where RNA polymerase stops synthesizing RNA and releases the newly formed RNA molecule from the DNA template.