There are, for instance, sausage-shaped mitochondria , which are the cell's factories, and the flattened sacks of the Golgi bodies , where protein and carbohydrate are packaged for release from the cell. The nucleus Most plant and animal cells contain an inner part called a nucleus , which is the cell's control centre. The nucleus is surrounded by a nuclear membrane. The nucleus contains the blueprint for an entire new plant or animal. Cells with a nuclear membrane are called eukaryotic .
Bacteria are prokaryotic , which means they have no nuclear membrane.
All of them grew from a single cell made by the fusion of a sperm cell from your father and an egg cell from your mother. This one cell contained all the instructions necessary to make you. It divided many times to produce the millions and millions of cells in your body. So although cells have many shapes and tasks, they all have the same basic structure. Cells are constantly wearing out and being replaced by new ones.