Exon

Definition

An exon is a segment of a gene that contains coding information for a protein and is retained in the final mRNA after the process of RNA splicing. Exons are essential for producing functional proteins, as they specify the amino acid sequences that will be translated. In contrast to introns, which are non-coding regions removed during RNA processing, exons are crucial for gene expression and ultimately influence the traits and functions of an organism.

5 Must Know Facts For Your Next Test

1. Exons can vary significantly in length and number within different genes, contributing to the diversity of proteins produced by an organism.
2. Alternative splicing can occur, where different combinations of exons are joined together, resulting in multiple protein isoforms from a single gene.
3. The presence of exons allows for the evolutionary flexibility of genes, as new exons can be added or existing ones modified to create new protein functions.
4. The identification of exons is essential in genomics and bioinformatics for understanding gene structure and function.
5. Mutations within exons can directly affect protein function and lead to various genetic disorders or diseases.

Review Questions

• How do exons contribute to the diversity of proteins produced in an organism?
  • Exons contribute to protein diversity through mechanisms like alternative splicing, where different combinations of exons can be included in the final mRNA transcript. This allows a single gene to produce multiple protein isoforms, each with potentially distinct functions. By varying the arrangement and combination of exons, organisms can adapt their protein production to meet specific biological needs or environmental changes.
• Discuss the role of exons and introns in the context of RNA splicing and how this affects gene expression.
  • Exons are retained during RNA splicing and form the coding regions of mature mRNA, while introns are non-coding segments that are removed. This process is critical for accurate gene expression, as only exons translate into functional proteins. The interplay between exons and introns ensures that the final mRNA transcript is properly processed, allowing for precise control over which proteins are synthesized and how they function within the cell.
• Evaluate the implications of mutations in exons on protein function and potential disease outcomes.
  • Mutations occurring within exons can lead to changes in the amino acid sequence of proteins, which may alter their structure and function. Depending on the nature of the mutation, this can result in loss of function, gain of function, or even entirely new functions for the affected protein. Such alterations can contribute to various genetic disorders or diseases, highlighting the importance of studying exon sequences in understanding disease mechanisms and developing targeted therapies.

Related terms

intron:

A non-coding segment of a gene that is removed from the precursor mRNA during RNA splicing.

mRNA (messenger RNA): A type of RNA that conveys genetic information from DNA to the ribosome, where it serves as a template for protein synthesis.

RNA splicing: The process by which introns are removed from precursor mRNA and exons are joined together to form mature mRNA.