Nuclear Material – Definition: In a eukaryotic nucleus, the complex of DNA and associated proteins (primarily histones) is called:
Correct Answer: chromatin
Introduction / Context:DNA does not exist naked in the nucleus. It is packaged with proteins in an organized structure essential for gene regulation and chromosome architecture.
Given Data / Assumptions:
- We are in a eukaryotic nucleus.
- Proteins involved are predominantly histones, plus non-histone proteins.
Concept / Approach:DNA winds around histone octamers to form nucleosomes, which fold into higher-order structures. This DNA-protein complex is chromatin. Nucleoplasm is the nuclear matrix/sol; plasmids are extra-chromosomal DNA in prokaryotes; nucleoid refers to prokaryotic DNA region.
Step-by-Step Solution:1) Identify the described mixture: DNA + proteins.2) In eukaryotes, that definition maps to chromatin.
Verification / Alternative check:During mitosis, chromatin condenses to visible chromosomes—consistent with the definition.
Why Other Options Are Wrong:Nucleoplasm is the nuclear fluid. Plasmids and nucleoid are prokaryotic terms.
Common Pitfalls:Confusing “chromatin” with “chromatid”; a chromatid is one of two identical halves of a replicated chromosome.
Final Answer:chromatin