The nucleus is composed largely of:

The nucleus is primarily composed of DNA, which is the genetic material in eukaryotic cells. DNA is organized into structures called chromatin, which condense to form chromosomes during cell division. The nucleus serves as the cell's command center, housing not just the DNA but also the machinery required for transcription—the process of synthesizing RNA from DNA. This is crucial for the expression of genes and the production of proteins, which take place in the cytoplasm after RNA is transported out of the nucleus.

While RNA is indeed found in the nucleus, it is not the main structural component; rather, RNA is synthesized from the DNA template. Ribosomes, though essential for protein synthesis, are not housed in the nucleus; they are found in the cytoplasm or attached to the endoplasmic reticulum. Glycoproteins are involved in various cellular functions and are predominantly found in the cell membrane or secreted outside the cell rather than within the nucleus itself. Thus, the primary composition of the nucleus is accurately identified as DNA.