Which organelle does not have a double membrane?

Lysosomes are organelles bound by a single membrane. Lysosomes produce hydrolytic enzymes, which are catalytic proteins used by the cells to digest molecules from antigens, other organelles, complex sugars and proteins.

The digestion process begins when foreign particles enter the cell. Enzymes released by the lysosomes break down the complex molecules within these particles. Lysosomes can also undergo the digestion process by breaking down the cell organelles for nutrients when food sources are scarce. The inability of lysosomes to manufacture specific enzymes or break down foreign particles is indicative of serious medical conditions, such as Tay-Sachs disease and Gaucher's disease.