Skip to content
Login Register

#DNA segments

2 public questions tagged with this topic.

Transcription Basics

Introns are

Introns are intervening sequences interspersed between exons within transcription unit, transcribed into precursor RNA but excised during nuclear processing. Detected as discontinuities between genomic DNA and cDNA, introns vary from few base pairs to hundreds of kilobases, typically beginning GU and ending AG in mammals. Group I, II, and spliceosomal introns removed by different mechanisms; spliceosomal introns excised via lariat formation catalyzed by U1, U2, U5 snRNPs. Though non-coding, introns harbor regulatory RNAs, influence mRNA export, nonsense-mediated decay, and alternative splicing

Ref: Lodish Molecular Cell Biology Chapter 9: Introns intervening sequences definition splicing; Alberts Chapter 6 Intron lariat removal

View Details
Transcription Basics

Exons are defined as DNA segments that

Exon terminology from expressed region denotes segments of transcription unit that persist in mature messenger RNA after intron removal by spliceosome. Exons include both protein-coding stretches and non-coding 5' and 3' untranslated regions that influence stability and translation efficiency. In pre-mRNA, exon-intron boundaries defined by conserved GU at 5' splice site, AG at 3' site, and branch adenosine. Spliceosome catalyzes two sequential transesterification reactions ligating exons. Because exon shuffling creates novel domain combinations, retention rather than removal defines exon funct

Ref: Alberts Chapter 6: Exon definition remains in mature mRNA after splicing; NCBI Bookshelf Splicing exonic retention mechanism

View Details