DNA Biology Practice Test

Tightly compacted, inactive chromatin is heterochromatin. This state is highly condensed and generally inaccessible to transcription machinery, so genes in these regions are not expressed. In contrast, euchromatin is loosely packed and transcriptionally active, which is the opposite of what the question describes. The nucleosome is simply the basic unit of chromatin structure—the DNA wrapped around histone proteins—not a description of the overall condensation state. A Barr body is an example of heterochromatin: it's the inactivated X chromosome seen in some female cells, illustrating condensed, transcriptionally silent chromatin. So the term that best fits tightly compacted, inactive chromatin is heterochromatin.