nonwatson/crick nucleosides

[alexandertg6]

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There is so much information about nonwatson/crick nucleosides like inosine, dihydrogen uridine etc. but what do we probably need to know for the MCAT if anything at all?

 

[RogueUnicorn]

none

 

[MegaSpectacular]

none

lol. Yeah you don't need to know that stuff. There is so much more going on in biology than we know, they just recently figured out how exons wrap around histones (like less than a year ago!), so just use your prep book and the bio topics guide on AAMC.

 

[StIGMA]

To the last comment, X-ray structures of DNA and histones have been around since at least '97 (http://www.ncbi.nlm.nih.gov//pubmed/9305837), and I don't feel like looking harder. Perhaps you are referring to the dynamic movement of histones like would be seen during transcription.

Second, Watson-Crick pairing refers specifically to DNA pairing. You definitely need to know that U replaces T in RNA, and U can pair with both A and G.

Studying atypical nucleosides would not be the most efficient use of your study time and can be ignored.

 

[MegaSpectacular]

To the last comment, X-ray structures of DNA and histones have been around since at least '97 (http://www.ncbi.nlm.nih.gov//pubmed/9305837), and I don't feel like looking harder. Perhaps you are referring to the dynamic movement of histones like would be seen during transcription.

I'm referring to what I said, EXONS not DNA being wrapped around histones. Read my statement again. Yes they did know DNA wrapped around histones 13 years ago but not specifically EXONS. This was just published Aug 2009 in Natural and Structural Molecular Biology


Chromatin organization marks exon-intron structure

Schraga Schwartz1, Eran Meshorer2 & Gil Ast1

Received 6 May; accepted 21 July; published online 16 August 2009; doi:10.1038/nsmb.1659

Here is the abstract:

An increasing body of evidence indicates that transcription and splicing are coupled, and it is accepted that chromatin organization regulates transcription. Little is known about the cross-talk between chromatin structure and exon-intron architecture. By analysis of genome-wide nucleosome-positioning data sets from humans, flies and worms, we found that exons show increased nucleosome-occupancy levels with respect to introns, a finding that we link to differential GC content and nucleosome-disfavoring elements between exons and introns. Analysis of genome-wide chromatin immunoprecipitation data in humans and mice revealed four specific post-translational histone modifications enriched in exons. Our findings indicate that previously described enrichment of H3K36me3 modifications in exons reflects a more fundamental phenomenon, namely increased nucleosome occupancy along exons. Our results suggest an RNA polymerase II–mediated cross-talk between chromatin structure and exon-intron architecture, implying that exon selection may be modulated by chromatin structure.

The study was done using GWAS and would not have been possible 13 years ago as #1 they didn't have all these genomes sequenced, #2 they didn't have databases available to do such tasks.

 

[DrYoda]

There's a lot of bio info not tested on the MCAT. That's why you review books are helpful, because they cover just required materials.

On the right side of the below link there are outlines for what info is covered on the different sections.

http://www.aamc.org/students/mcat/preparing/creatingstudyplan.htm