AAMC FL Practice Exam

Which of the following describes the formation of isoforms?

1. Using identical exons in transcription

2. Utilizing different exons through alternative splicing

3. Incorporating mutations during translation

4. Employing post-translational modifications

The correct answer is: Utilizing different exons through alternative splicing

The formation of isoforms refers to the generation of different versions of proteins that can arise from a single gene. This process primarily involves the utilization of different exons through alternative splicing. During transcription, the pre-mRNA produced from a gene can be spliced in various ways to include or exclude certain exons. This results in multiple mRNA transcripts that can encode distinct protein isoforms with potentially different functions, activities, or regulatory mechanisms. Alternative splicing contributes significantly to the diversity of proteins in the cell, allowing for complex regulatory networks and responses to various cellular conditions. This mechanism explains why a single gene can give rise to multiple protein products, contributing to the complexity of eukaryotic gene expression. The other options do not accurately describe isoform formation: using identical exons would not generate isoforms, incorporating mutations during translation relates to errors or changes in protein synthesis rather than different variants, and post-translational modifications refer to changes made to a protein after it has been synthesized and do not involve the genetic basis of isoform generation.