I have three younger siblings, two are sisters and one is a brother. You will already know that you and your sibling are identical because you were made from the same sperma and egg. Have a look at my genetics page if you want to know more about inheritance. The cytoplasm is the part of the cell which does all the work. This energy containing chemical is produced by tiny organelles in the cell called mitochondria.
Muscle cells contain two very special chemicals called actin and myosin.
These are made of protein and they can join together to form actinomyosin. When a nerve impulse simulates a muscle it makes the actinomyosin contract. The cell membrane controls what comes into and goes out of the cell. Cell membranes are semi-permeable. That means that they allow some things to pass through and prevent other things from passing through.