1. STRUCTURE OF CHROMATIN
Lindsey Suttle, Aaron Alejandro, Christine Nam and Aruna Iyer

2. BUILDING BLOCKS
Nucleosome: The basic, beadlike unit of DNA packaging in eukaryotes, consisting of a segment of DNA wound twice around a protein core composed of two copies of each of four types of histone.
Histone: A small protein with a high proportion of positively charged amino acids that binds to the negatively charged DNA
It plays a key role in its chromatin structure. 

3. PROTEIN SCAFFOLDING
Protein Scaffolding: The H1 histone that attaches to the histones and chromatin for support
Proteins called histones have a high proportion of positively charged amino acids and bind to negatively charged DNA. The DNA-histone complex is chromatin in its most basic structure. Histones are similar in most eukaryotes. Unfolded chromosomes look like beads on a string. Each bead and its DNA is called a nucleosome. The nucleosome bead is DNA wound around a protein core made of two of these histones: H2A, H2B, H3, and H4. H1, another histone attaches to the DNA near the bead when the chromatin undergoes the next level of packing. 

4. CHROMATIN FIBER
Chromatin fiber: the folded complex of DNA and histone proteins that is roughly 30nm in thickness that are very long and not visible with a light microscope.
The chromatin fibers coil up to form chromosomes
Also known as 30-nm chromatin fiber or 30-nm fiber
Looped domain: the loop formed by chromatin fiber
This attaches to a chromosome scaffold made of nonhistone proteins.

5. 2 TYPES OF INTERPAHSE CHROMATIN
Heterochromatin: highly condensed state of chromatin
Visible through a light microscope
Does not undergo transcription
Euchromatin: lightly compacted chromatin
Undergoes transcriptions
Found in both eukaryotic and prokaryotic cells

6. MODIFICATIONS
DNA methylation: the attachment of methyl groups (-CH3) to DNA bases (after DNA is synthesized)
Methylation can turnoff genes
Demethylation is when the extra methyl groups are removed
Demethylation can activate genes
Protects and stabilizes DNA
Histone acetylation: when an acetyl group (-COCH3) is attached to certain amino acids of histones.
When a histone is acetylated it changes shape making the DNA fit less tightly allowing for other proteins to bind for transcription.
Deacetylation is the removal of acetyl groups.

7. YOUTUBE
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8. PREVIOUS VOCAB Nucleic acids Dehydration synthesis Light microscope
Proteins
R groups
Mitosis/meiosis

9. OBJECTIVE TERMINOLOGY
Chromatin
Chromosome
Looped domains
Heterochromatin
Nucleosome “beads”
Histones
Proteins scaffolding
DNA methylation
Histone acetylation
Euchromatin

10. REVIEW QUESTIONS What makes up Protein Scaffolding?
Histones, DNA, nucleosomes
Four histones with DNA wrapped twice around the four histones creates what is known as ______
Nucleosomes
What does DNA methylation do for the DNA?
Turns off genes, protects, and stabilizes DNA
Histone Acetylation occurs to let what other process occur?
Transcription, by making the fit of the DNA looser
What does the looped domain attach to?
The chromosome scaffold (non histone proteins)

11. REVIEW QUESTIONS CONTINUED
What is the main difference between euchromatin and heterochromatin?
The tightness in which they are compacted. Heterochromatin is highly condensed form of chromatin and euchromatin is lightly compacted
In what type of cells is euchromatin found?
Eukaryotic and prokaryotic cells
Which form of chromatin undergoes transcription?
Euchromatin
Contrast the structure of chromatin before and after Interpahse.
Before Interpahse the chromatin is just chromatin after Interpahse the chromatin is wound around histones and is in the form of chromosomes

12. JUST FOR FUN
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