DNA and chromatin regulation | Biomolecules | MCAT | Khan Academy

Created by Tracy Kim Kovach.

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[sunnyyoda]

Absolutely, phenomenal job! This is why I love and follow Khan Academy.

[sabrinarun]

DNA methylation is a process by which methyl groups are added to the DNA molecule. Methylation can change the activity of a DNA segment without changing the sequence. When located in a gene promoter, DNA methylation typically acts to repress gene transcription.

[ABeardedDad]

Excellent video, just perfectly elucidated the concepts of Heterochromatin and Euchromatin for me thankyou!!

[dingding]

3:54 I think actually CpG islands are where cytosine is adjacent to guanine, not bound to guanine. When adjacent, they are separated by a phosphate group (hence the p in CpG); normally, CpG is more prone to mutation, so a region rich with CpG can be examined to see if it is highly conserved i.e. important not to mess with too much.

[APS]

This was great! Just thought I'd point out though that CpG islands refer to the fact that Cytosine is linked via a phosphodiester bond with Guanine along the same strand of DNA. It's not referring to the fact that Cytosine forms hydrogen bonds with Guanine across complementary strands (although this does happen). Other than that, keep up the good work :) These videos help me tons for my uni exams

[MADDIEHUBBS]

This is an extremely helpful video. Watching this in 3rd year of university, THANK YOU!!

[pastimepursuit]

0:01-0:12, 0:26-0:37, 0:57-3:59 (HAT: knot can't wrap up perfectly. HDAC: no knot; eu vs hibernating chromatin; acetylation vs methylation; methyltransferase, CpG islands), 4:35-5:18 (CpG halts transcription proteins and MBD).

[Jonathan-rfcp]

CpG islands are long repeats of CG twomers. The fact that C pairs with G is irrelevant and the 'p' in 'CpG' stands for phosphodiester.

[charleyjr.iriarte]

Thanks for teaching about the chromatin regulation.

[jellyfishstars]

Wow. Extremely informative and helpful. Thank you

[MissBeautyE]

Just a little thing I noticed - CpG islands are not named that way because C base pairs with G, but because of the dinucleotide C - phosphodiester bond - G.

[rpe]

dang, I wish I actually took the time to learn cursive in grade school

[jgerka]

Talking about DNA and not mentioning blood and blood types is like having a debate with Gorillas about DNA.

[ksharm]

I don't believe that it's accurate that chromatin is supercoiled. Supercoiling happens when a replication bubble compresses the DNA on either side of the bubble.

[despoinabeni]

If only I could translate in Greek language …what disappointment …