DNA and chromatin regulation | Biomolecules | MCAT | Khan Academy
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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.
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).
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.
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Thank you it was really helpful
You are the worst moderator…try to teach properly woman!! The males in other channel if Khan Academy are so much better!
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The importance of gene expression regulation is to conserve the expending of energy by only producing the necessary proteins.
Histone acetyltransferase are enzymes adding an acetyl group to the amino acid tail of histone, which leads to the uncoiling of chromatin structure and allowing it to be accessed for transcription, which is also known as euchromatin.
– Euchromatin is loosely-packaged, actively being transcribed, includes many genes, and many unique DNA sequences
Histone deacetyltransferase are enzymes removing an acetyl group to condense the chromatin sturcture leading to less transcription, which is known as heterochromatin.
-Heterochromatin is tightly-packaged, not actively being transcribed, doesn't include many genes, and has many repetitive sequences.
Gene silencing is done by combining DNA methylation with Histone Deacetylation. Gene silencing is a more permanent mechanism to down-regulate the transcription of genes. It is adding a methyl group (CH3) to cytosine in a cytosine-rich CpG island. This can lead to two effects. The first effect is methylation which impedes the binding of transcriptional proteins to the gene. The second effect is methylated DNA bound by methyl CpG-binding domain proteins (MBDs) which recruits additional proteins to the locus of the chromosome or to histone deactylases, which formas heterochromatin.
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.
This is an extremely helpful video. Watching this in 3rd year of university, THANK YOU!!
Wow. Extremely informative and helpful. Thank you
Absolutely, phenomenal job! This is why I love and follow Khan Academy.
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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.
If we modify this, is it possible to be immortal?
dang, I wish I actually took the time to learn cursive in grade school
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
Thanks for teaching about the chromatin regulation.
Excellent video, just perfectly elucidated the concepts of Heterochromatin and Euchromatin for me thankyou!!
VERY NICE thank you