Lysosomes are membrane-bound enzymes. With this enclosed structure, the cell can utilize the enzymes to hydrolyze macromolecules at an efficient pH without damaging its own structures.
Peroxisomes contain enzymes that transfer hydrogen to oxygen. The cell uses this process to break down fatty acids which are then transported to the mitochondria as fuel for cellular respiration.
A vacuole is a cell's storage facility. The functions of a vacuole, the most noticable structure in a plant cell, include the storage of metabolic byproducts, pigments and animal poisons.