All living things are made of cells, which are the basic building blocks of life. Animal cells contain a nucleus that controls cell activities, cytoplasm in the center where reactions occur, and a cell membrane that regulates what enters and exits. Plant cells have these parts as well as a cell wall, vacuoles that store water, and chloroplasts for photosynthesis. While animal and plant cells share some components, plant cells differ in having a cell wall, vacuoles, and chloroplasts.