Chromatin structure Flashcards
Question 3 M
At 3 x 109 bp, the human haploid genome must undergo several phases of packaging to fit into the nucleus. Which is the proper order of these condensations from the lowest to the highest compaction ratio?
Answer
A. 10-nm fiber, 30-nm fiber, nucleosome, condensed loop
B. Condensed loop, 10-nm fiber, 30-nm fiber, nucleosome
C. Condensed loop, 30-nm fiber, 10-nm fiber, nucleosome
D. Nucleosome, 10-nm fiber, 30-nm fiber, condensed loop
E. Nucleosome, condensed loop, 10-nm fiber, 30-nm fiber
D. Nucleosome, 10-nm fiber, 30-nm fiber, condensed loop
It’s the most prevalent conformation of DNA and is double-helical and right-handed
Helix is 20 Å wide
Helix pitch (rise per turn) is 34 Å
Base pairs per turn of the helix is 10
Helix rise per base pair is 3.4 Å or 0.34 nm
The two strands of the helix are antiparallel and are plectonemically coiled (the two strands are wrapped around each other such that they cannot be separated without unwinding the helix)
Is it
A. A-DNA
B. B-DNA
C. C-DNA
D. Z-DNA
B. B-DNA
It’s s right-handed
It is wider (26Å diameter), shorter (28 Å/turn) and denser (11 bp/turn) than B-DNA
It forms under conditions of low humidity (e,g presence of ethanol);
It’s found in DNA-RNA & RNA-RNA helices
Is it:
A. A-DNA
B. B-DNA
C. C-DNA
D. Z-DNA
A. A-DNA
it is left-handed
It’s formed by alternating Pur and Pyr bps and as such the phosphates zig-zags (It has possible role gene expression and regulation?)
It is thinner (18Å diameter), longer (45 Å/turn) than B-DNA, & has 12 bp/ turn
Is it:
A. A-DNA
B. B-DNA
C. C-DNA
D. Z-DNA
D. Z-DNA
What conditions favor Z-DNA conformation
Histones can bind eukaryotic DNA tightly because they have a high isoelectric point. This is due to their enrichment of in the amino acid
A. [ ] arginine
B. [] aspartate
C.[] glycine
D.[] proline
E. [] tyrosine
A. Arginine
It is the transcriptionally active level of chromatin structure, and it has a compaction or condensation ration of about 6-7
A. [] beads-on-a- string chromatin
B. [] chromosome at the metaphase of mitosis C.[] loops domain
D.[] naked DNA
E. [] solenoid
A. Beads on a sting chromatin
