Harris Chromosome structure
Terms
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During most of the cell cycle DNA is present in the nucleus as______.
- euchromatin
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Histones + DNA =
- Nucleosomes
- How's eukaryotic DNA different?
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Highly repetitive DNA sequences (near centromeres or in telomeres)Contain introns (really long)Exons: pretty smallLessons from Human Genome project.
Only 2% DNA is protein coding sequence.
Functions unknown for over 1/2 discovered genes
Many animals/plant have more DNA than humans.
- T/F: Genes evely spread on chromosomes in humans.
- False.
- T/F: Human genes are about 99.9% the same
- True
- Tell me about bent DNA.
Found with long stretches of AT; Around a protein; With a drug
DNA is flexible
- What are centromeres?
- Near midpoint of chromosomes; attach to mitotic spindle; consist of highly repetitive DNA sequences
- What are histones? (made of)
Basic proteins
lots of lys and arg; (+) at pH 7.4
5 classes: H1, H2a, H2b, H3, H4
Bind compactly to DNA
Are acetylated and ppylt'd
- What are nucleosomes (specific)?
146 BP of DNA. 2 molecules Each of H2A, H2B, H3, and H4- What are protein scaffolds?
Form domains of nucleosomes.
Turn beads-on-string to a solenoid.
- What are telomeres?
At the end of liner DNA w/ TTAGGG-3' repeats
Maintain integrity at chromosome ends
- What comprises chromosomes?
DNA (a chromatid = single, linear DNA)
Histones
Nonhistones
- What does H1 do?
- Wrap DNA around the other histones
- What kinds of DNA are there?
A
B
Z
- What winds up DNA?
- Enzymes. (Like topoisomerase II)
- What's A DNA?
Found when DNA binds w/ RNA.
Also when DNA binds in high humidity.
Fatter, bigger hole in center.
- What's B DNA?
- What Watson and Crick discovered. Generally what we find.
- What's supercoiling?
1 way to bend DNA.
Negative (right handed) is easier to separate into single strands. Underwind
(+) - left handed; overwind
They are topoisomers
- What's Z DNA?
Left-handed. Skinner.
Zig Zag helix.
Not found in vivo.