Transcription

Definition

Transcription is the biological process through which the genetic information encoded in DNA is copied into messenger RNA (mRNA). This process is essential for gene expression and occurs in two main stages: initiation and elongation, followed by termination. The resulting mRNA serves as a template for protein synthesis during translation, linking the information in genes to the proteins that carry out cellular functions.

5 Must Know Facts For Your Next Test

1. Transcription begins when RNA polymerase binds to the promoter region of a gene, unwinding the DNA strands.
2. The RNA synthesized during transcription is complementary to the DNA template strand and uses uracil instead of thymine.
3. Eukaryotic cells undergo post-transcriptional modifications, such as adding a 5' cap and a poly-A tail, to stabilize mRNA before it exits the nucleus.
4. Transcription can be regulated by various factors, including transcription factors and enhancers, which can enhance or repress gene expression.
5. In prokaryotic organisms, transcription occurs simultaneously with translation in the cytoplasm due to the lack of a nuclear membrane.

Review Questions

• Explain how transcription initiates and what role the promoter plays in this process.
  • Transcription initiates when RNA polymerase binds to the promoter region of a gene, which is a specific sequence of DNA located upstream of the coding region. The promoter provides a recognition site for RNA polymerase and facilitates its attachment to the DNA. Once bound, RNA polymerase unwinds the DNA strands and begins synthesizing mRNA based on the DNA template. The interaction between RNA polymerase and the promoter is crucial for determining where transcription starts.
• Discuss how post-transcriptional modifications affect mRNA stability and function in eukaryotic cells.
  • Post-transcriptional modifications, such as the addition of a 5' cap and a poly-A tail, play vital roles in mRNA stability and function in eukaryotic cells. The 5' cap protects mRNA from degradation and assists in ribosome binding during translation initiation. The poly-A tail enhances mRNA stability by preventing degradation by exonucleases and facilitates export from the nucleus to the cytoplasm. These modifications are essential for ensuring that mRNA is properly processed before it can be translated into proteins.
• Analyze how transcription regulation can impact cellular function and development.
  • Transcription regulation plays a crucial role in controlling gene expression, impacting cellular function and development. Various elements, such as transcription factors, enhancers, and silencers, can either enhance or repress transcription in response to internal signals or environmental cues. This regulation allows cells to adapt to changing conditions, differentiate into specialized cell types, or respond to developmental signals. Consequently, disruptions in transcription regulation can lead to diseases such as cancer or developmental disorders, highlighting its significance in maintaining normal cellular processes.

Related terms

RNA Polymerase: An enzyme responsible for synthesizing RNA from a DNA template during transcription.

Promoter: A specific DNA sequence located upstream of a gene that serves as the binding site for RNA polymerase and initiates transcription.

Post-transcriptional Modification: The processes that mRNA undergoes after transcription, including capping, polyadenylation, and splicing, which prepare it for translation.