"Although the cell is the “most basic” unit of life, it is structurally and functionally complex. A cell can be thought of as a mini-organism consisting of tiny organs called organelles. The organelles are structural and functional units constructed from several macromolecules bonded together. A typical animal cell contains the nucleus, which houses the genetic material DNA; mitochondria, which generate energy; ribosomes, which produce protein; the endoplasmic reticulum, which is a packaging and transport facility; and the golgi apparatus, which distributes macromolecules. In addition, animal cells contain lysosomes and peroxisomes, which break down macromolecules and destroy foreign invaders. All of the organelles are anchored in the cell’s cytoplasm via a cytoskeleton. The cell’s organelles are isolated from the surrounding environment by a plasma membrane."