A, C, E only is correct for alternative splicing truths. It boosts protein diversity from single genes, alters protein localization via isoform-specific signals, and explains human proteome complexity from ~20,000-25,000 genes.

Question Breakdown

Alternative splicing (AS) generates multiple mRNA isoforms from one pre-mRNA by variable exon/intron selection, expanding proteome diversity post-transcriptionally. This multi-statement question tests core AS principles against misconceptions.

Statement Analysis

A: Increases proteins from each gene

True. AS produces distinct isoforms (e.g., 95% human multi-exon genes), vastly amplifying proteome from limited genome.

B: Step in post-translational regulation

False. AS occurs co-transcriptionally/pre-mRNA processing; post-translational covers modifications like phosphorylation.​

C: Changes protein localization

True. Isoforms gain/lose localization signals (e.g., nuclear export, mitochondrial targeting), directing proteins to organelles.​

D: Removal of alternative introns

False. AS involves exon inclusion/exclusion or intron retention; introns are obligatorily removed in constitutive splicing.​

E: Humans produce hundreds of thousands proteins from 25,000 genes

True. ~20-25k genes yield >100k proteins via AS (plus PTMs), solving “one gene-one protein” paradox.​

Correct Option: A, C, E only

True for alternative splicing includes expanding proteins per gene, altering cellular localization, and enabling proteome complexity from ~25,000 human genes – key to your molecular biology studies.

AS Mechanisms & Impacts

• Exon skipping/inclusion: Most common, creates functional diversity.​

• Mutually exclusive exons: Swaps domains for localization/function.​

• Intron retention: Often regulatory/NMD-targeted.​

~15% disease-linked AS variants underscore precision.​

Proteome Expansion

One gene → dozens isoforms (e.g., DSCAM: 38k isoforms). Localization shifts via signal peptide changes direct trafficking.​