There are two main types of living cells: prokaryotic and eukaryotic. Prokaryotic cells lack a nucleus and have DNA found in a single chromosome, while eukaryotic cells have a nucleus containing DNA. Eukaryotic cells are generally larger and multicellular, found in animals and plants. Cell membranes control what enters and exits cells through selective permeability and transport mechanisms like diffusion, osmosis, and active transport. Cell division occurs through mitosis and meiosis to allow growth and reproduction.