Define nucleus and nucleolus

The nucleolus is a structure found in the nucleus of cells and it forms around specific chromosomal regions in the nucleus of eukaryotic cells, and is made up of proteins and ribonucleic acids. Its main function is to transcribe ribosomal RNA (rRNA) and combine it with proteins to form incomplete ribosomes

Nucleus

the central and most important part of an object, movement, or group, forming the basis for its activity and growth.

Nucleolus

a small dense spherical structure in the nucleus of a cell during interphase.