The three main/basic parts of the cell are:
Cell Membrane (Plasma Membrane)
Cytoplasm
Nucleus
Each cell is surrounded by a lipid-rich Cell membrane (also called the Plasma Membrane) that forms a boundary between the cell and its environment.
The membrane encloses the Cytoplasm, which includes all cell contents (except the Nucleus, in cells that have one). Cytosol is the fluid of Cytoplasm.
Nucleus is the central part of an atom, and the process of milk production and secretion begins here; the organelle that contains DNA in eukaryotic cells.