Question

Which of the following is the correct increasing order of chromosome organization?
A.
nucleosome beads, 30 nm fibers, looped domains
B.
nucleosome beads, mitotic condensation, looped domains
C.
30 nm fibers, looped domains, mitotic condensation
D.
looped domains, nucleosome beads, 30 nm fibers

Answer 1

Answer:

I think option B is the correct one

Answer 2

Answer:

Cells package their DNA not only to protect it, but also to regulate which genes are accessed and when. Cellular genes are therefore similar to valuable files stored in a file cabinet — but in this case, the cabinet's drawers are constantly opening and closing; various files are continually being located, pulled, and copied; and the original files are always returned to the correct location.

Of course, just as file drawers help conserve space in an office, DNA packaging helps conserve space in cells. Packaging is the reason why the approximately two meters of human DNA can fit into a cell that is only a few micrometers wide. But how, exactly, is DNA compacted to fit within eukaryotic and prokaryotic cells? And what mechanisms do cells use to access this highly compacted genetic material?

What Are Chromosomes?

Cellular DNA is never bare and unaccompanied by other proteins. Rather, it always forms a complex with various protein partners that help package it into such a tiny space. This DNA-protein complex is called chromatin, wherein the mass of protein and nucleic acid is nearly equal. Within cells, chromatin usually folds into characteristic formations called chromosomes. Each chromosome contains a single double-stranded piece of DNA along with the aforementioned packaging proteins.

A circular cell-cycle diagram shows the degree to which chromatin is condensed inside a cell during the five stages of mitosis. Each stage is labeled and numbered beside an illustration of a cell. At the center of each cell is a nucleus containing chromatin. The illustration for stages 1 (interphase), 2 (prophase), and 3 (metaphase) show only a single cell. Stage 4 (anaphase) shows a cell in the process of dividing: two distinct cell shapes with two developing nuclei are shown. In stage 5 (telophase), two separate cells are shown, each with its own nuclei and chromatin.