Cells are the basic units of life and come in two main types - prokaryotic and eukaryotic. Prokaryotic cells lack a nucleus and organelles, while eukaryotic cells have a nucleus surrounded by a membrane and membrane-bound organelles. Organelles such as the nucleus, mitochondria, endoplasmic reticulum, Golgi complex, lysosomes, vacuoles, chloroplasts and cell wall allow cells to carry out essential functions of life like metabolism, transport, waste removal and photosynthesis. The document outlines the key structures and functions of organelles in plant and animal cells.