Many of the activities of eukaryotic cells are carried out by functional subassemblies known as organelles. Organelles are complex, ordered arrays of macromolecules. Every cell typically contains hundreds of different kinds of macromolecules that function together to generate the behavior of the cell. Don't lose sight of the molecular basis of organelle function. Whether you are conceptualizing endoplasmic reticula, the Golgi apparatus, a centriole, or a ribosome, always strive to include the molecular scale in your conceptual picture. Strive to integrate with your understanding of cell biology with basic chemistry.