Question

The figure clearly depicts the nucleolus, a nuclear structure that looks like a large, dark region when stained. The other dark, speckled regions in this image are the locations of particularly compact chromosomal segments called ________________.

(a) euchromatin
(b) heterochromatin
(c) nuclear pores
(d) nucleosomes

Answer 1

The dark, speckled regions other than the nucleolus in the figure of a nucleus are known as heterochromatin, which contains tightly packaged genetic material that is generally not expressed.

Step-by-step explanation:

The other dark, speckled regions in the image of the nucleus, besides the nucleolus, represent the locations of compact chromosomal segments known as heterochromatin. Heterochromatin is the tightly packaged region within the nucleus that generally contains genes that are not expressed (not actively transcribed to make a product), and it is typically found in the regions of the centromere and telomeres. In contrast, the less dense region, called euchromatin, usually contains genes that are actively transcribed, and the DNA here is packaged around nucleosomes but not further compacted.