cell basic unit of structure and function in a living thing cell membrane forms the outside border of the cell nucleus directs the cell’s activities and holds information that controls a cell’s fuction cytoplasm tissue made of clear, jellylike substance that contains many cell structures group of similar cells that perform the same function muscle tissue nervous tissue connective tissue epithelial tissue organ body tissue that contracts, or shortens, making body parts move carries electrical messages back and forth between the brain and other parts of the body provides support for your body and connects all its parts covers the surface of your body, inside and out structure that is made up of different kinds of tissue organ system group of organs that work together carrying out major functions