Histone Acetylation & DNA Methylation + Practice Problem | MCAT 

TL;DR: Histone acetylation neutralizes the positive charge on lysine, reducing the Coulombic positive-negative attractive force between the positively-charged histone and negatively-charged DNA. DNA methylation usually reduces transcription by reducing the availability of space for transcription factors and RNA polymerases.
Abstract of article by Shaw et al. on net charge on a protein: bit.ly/3i3exLa
Today’s MedCat video covers histone acetylation, histone deacetylation, DNA methylation, and finally a AAMC-derived practice problem that crosses over with the MCAT concept of the isoelectric point of a protein (pI). Histone acetylation, as the name suggests, is the process of using the enzyme histone acetylase to add an acetyl group to a lysine or arginine residue (usually lysine within the context of the MCAT). Histone deacetylation is the opposite: taking off that acetyl group. The major consequence of acetylation is reduction of positive charge, freeing the DNA from the positive-negative Coulombic attractive force so that the chromatin becomes more euchromatic and open to transcription. Unsurprisingly, the opposite happens with deacetylation.
DNA methylation is distinct from histone acetylation (and a related concept of histone methylation, which also tends to reduce transcription). It involves directly methylating the nitrogenous bases adenine and cytosine (which you should be able to recognize by sight!). This methylation reduces the space available for proteins like transcription factors and RNA polymerases, resulting in reduced transcription (i.e. gene expression).
Time Stamps:
Intro: (0:00)
Histone Acetylation & Deacetylation: (0:08)
DNA Methylation: (3:37)
AAMC-Derived Practice Problem: (5:21)
Outro: (7:55)
Comprehensive Amino Acid Playlist: bit.ly/3sMGBUG
Check out Aratasaki, the beat maker behind my intro and outro: bit.ly/2Pma5v0
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#mcat #histoneacetylation #dnamethylation
Histone Acetylation & DNA Methylation + Practice Problem | MCAT
Histone Acetylation & DNA Methylation + Practice Problem | MCAT
Histone Acetylation & DNA Methylation + Practice Problem | MCAT