LS 3 Study guide

LS 3 Study guide - mRNA- 5 Cap o Structure 7-methyl...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

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

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

Unformatted text preview: mRNA- 5 Cap o Structure 7-methyl guanylate 3 phosphates 2 ribose with and OH at the 2 or 3 carbon 5 to 5 linkage btwn the ribose-phosphate-ribose o Mechanism for Capping RNA triphosphatase removes 1 phosphate from 5 end of RNA Guanylyltransferase Adds GMP to 5 phosphate Forms 5-5 linkages S-adenosyl methionine (AdoMet) Adds methyl to methyl guanylate o Function Makes it easier for splicing Transportation out of the nucleus Prevents degrading of mRNA Enhances the translatability of mRNA- Poly (A) Tail o Mechanism CstF (cleavage stimulation factor)-binds to GU/U region and facilitates cutting CPSF (cleavage polyA specificity factor)-binds to the AAUAAA region facilitates cutting PAP (polyA polymerase protein) CF I and II (Cleavage factor)-binds to cutting site CstF and CPSF work together to cut CTD of RNA poly II helps stimuate the cutting After cleavage CF I and II fall off and CstF PolyA polymerase and CPSF start PolyA synthesis till 10nt oligos long PAB II (polyA binding protein) elongates till 250 nt long o Function protects RNA from degradation enhances translatability of RNA - Splicing o Differential splicing Truncation Alternative exons o Taking out the intron (noncoding regions of DNA to produce RNA) o Gives different expressions from the same sequence of DNA o There are highly conservative regions in the pre-mRNA o At the 5 end of the intron there is pGU and at the 3 end there is AGp o In the middle of the intron there is a conserved A. o Mechanism 2 sequential transesterificantion reactions The OH of the A attacks the phosphate of the pGU at the phospodiester bond, separating them. Then the remaining OH at the 3 end attacks the AGp phosphate also separating the bond The two ends of the intron as linked together as a result. snRNA splices the pre-mRNA 6 U-rich RNA in the nuclei U1 and U2 U1 - binds to the 5 of the intron and the 3 of the exon on the conservative regions - 3 major proteins sm U1-A specific to U 70k U2 binds to the 3 on the intron U2 binds but doesnt have the making U to the A that eventually sticks out to attack the phosphodiester bond of the pGU of the 5 of the intron Splicesomes mRNA snRNA proteins catalyzes splicing action DNA Replication - Semiconservative replications o Use one strand as the template o DNA unzips o Meselson and Stahl exp Use heavy N 15 Observed replication Originals all N15 Replicated will have various amounts of N14 depending on conservative/semiconservative/fragments Centrifuge in a CsCl density gradient to determine various density....
View Full Document

Page1 / 12

LS 3 Study guide - mRNA- 5 Cap o Structure 7-methyl...

This preview shows document pages 1 - 3. Sign up to view the full document.

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