Transcription and RNA Processing

Which feature best distinguishes mRNA processing in eukaryotes from prokaryotes?

Which feature best distinguishes alternative splicing from constitutive splicing in eukaryotic gene expression?

Which is the most common type of RNA processing defect causing β-thalassemia major in the Indian population?

A 32-year-old woman from Mumbai presents to the genetics clinic with a family history of progressive muscle weakness. Her father and paternal uncle both developed symptoms in their 40s and are now wheelchair-bound. Genetic testing reveals a mutation in the DMD gene (dystrophin gene) affecting the splice donor site of exon 45. The mutation does not completely prevent splicing but causes aberrant splicing with inclusion of a cryptic exon. Which of the following best explains the molecular consequence of this mutation and the resulting clinical phenotype?

A 28-year-old man from Bangalore is diagnosed with β-thalassemia major after presenting with severe hemolytic anemia, splenomegaly, and transfusion-dependent anemia since childhood. Molecular analysis reveals a mutation in the polyadenylation signal (AATAAA → AATGAA) in the 3′ untranslated region of the β-globin gene. Which of the following best explains why this mutation causes β-thalassemia despite the coding sequence being intact?