Post - lariat contains the intron that is still connected...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Post-Transcriptional RNA Processing The Chemistry of the Primary RNA Transcript Splicing Reaction and Alternative Splicing Splicing Step One In the first step of primary RNA transcript splicing, the 2' –OH on the branch point A attacks the phosphoryl group of the G in the 5' splice site. This G is the boundary between the 5' end of the intron and the 3' end of the adjacent exon. The attack leads to the breaking of the phosphodiester bond between the 3' end of the exon and the 5' end of the intron and the formation of a new phosphodiester bond between the branch point A and the 5' end of the intron. Figure% Primary RNA Transcript Splicing Reaction As is illustrated in the figure above, the first splicing step breaks the primary transcript into two pieces. One piece contains the 5' end of an exon, with a new free 3' –OH. The other piece is a strange looking structure that resembles a lasso and as a result is called a lariat structure. The
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: lariat contains the intron that is still connected to a second exon. Splicing Step Two In the second step of primary transcript splicing, the newly released 3' –OH of exon 1 attacks the phosphoryl group on the 5'-most nucleotide of exon 2. The resulting phosphodiester bond is the boundary between the intron and the second exon. The final products of the reaction are the two joined exons and the intron, which is still in the lariat structure. Alternative Splicing Alternative splicing is a way of introducing diversity to the gene products of transcription by creating multiple protein products from the same DNA sequence. Alternative splicing accomplishes this in two ways: 1) by splicing together exons from two different primary RNA transcripts in a process called trans- splicing; 2) by splicing out entire exons. Figure %: Exon-Exclusion Splicing...
View Full Document

This note was uploaded on 01/27/2012 for the course BIOLOGY BSC1005 taught by Professor Rodriguez during the Winter '09 term at Broward College.

Page1 / 2

Post - lariat contains the intron that is still connected...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online