Pre-mRNA

Definition

pre-mRNA, or precursor mRNA, is the initial RNA transcript produced during the process of transcription in eukaryotic cells. It is an intermediate step between the genetic information stored in DNA and the final functional mRNA molecule that will be used for protein synthesis.

5 Must Know Facts For Your Next Test

1. pre-mRNA contains both coding sequences (exons) and non-coding sequences (introns).
2. Splicing of pre-mRNA is required to remove the introns and ligate the exons to produce the mature mRNA.
3. Alternative splicing allows for the production of multiple mRNA variants from a single pre-mRNA molecule.
4. The 5' cap and 3' poly(A) tail are added to the pre-mRNA during post-transcriptional processing.
5. Proper processing of pre-mRNA is essential for the production of functional proteins in eukaryotic cells.

Review Questions

• Explain the role of pre-mRNA in the overall process of transcription and gene expression.
  • Pre-mRNA is the initial RNA transcript produced during transcription in eukaryotic cells. It contains both coding sequences (exons) and non-coding sequences (introns). The pre-mRNA must undergo further processing, including splicing to remove the introns and ligate the exons, as well as the addition of a 5' cap and 3' poly(A) tail, to produce the mature, functional mRNA molecule that can then be used as a template for protein synthesis. This processing of pre-mRNA is a critical step in the overall gene expression pathway.
• Describe the importance of alternative splicing in the context of pre-mRNA processing.
  • Alternative splicing is a crucial process that allows for the production of multiple mRNA variants from a single pre-mRNA molecule. By selectively including or excluding different exons, alternative splicing can generate diverse mRNA transcripts from the same gene, leading to the synthesis of different protein isoforms. This flexibility in pre-mRNA processing enables eukaryotic cells to greatly expand their protein repertoire and increase the functional complexity of the proteome, which is essential for cellular differentiation and adaptation to various physiological conditions.
• Analyze the potential consequences of errors or disruptions in pre-mRNA processing.
  • Proper processing of pre-mRNA is essential for the production of functional proteins in eukaryotic cells. Errors or disruptions in pre-mRNA processing, such as incorrect splicing or the failure to add the 5' cap or 3' poly(A) tail, can lead to the production of aberrant mRNA transcripts. These faulty mRNA molecules may then be translated into non-functional or even harmful proteins, which can have severe consequences for the cell and the organism. Disruptions in pre-mRNA processing have been implicated in the development of various genetic disorders and diseases, highlighting the critical importance of this process in maintaining cellular homeostasis and overall health.

Related terms

Transcription: The process of creating an RNA copy of a gene's DNA sequence, which is the first step in gene expression.

Splicing: The process of removing non-coding regions (introns) from the pre-mRNA transcript to produce the mature, functional mRNA.

Exon: The coding regions of a gene that are retained in the final mRNA molecule after splicing.