Animal cell. Coloured transmission electron micrograph (TEM) of a mammalian tissue culture cell. Taking up most of the top of the cell is the nucleus (redw), which contains the cell's genetic information in the form of DNA (deoxyribonucleic acid). The large bright structure in the nucleus is the nucleolus, which is responsible for producing components of ribosomes, the cell's protein-manufacturing organelles. Outside the nucleus is the cell cytoplasm. The pink bodies in the cytoplasm are mitochondria. These supply the cell with energy. The dark areas are membrane-bound vesicles or air bubbles introduced during sample preparation. Magnification: x4,500 when printed at 10 centimetres tall.