Lysosomes contain digestive enzymes, originating in part
from the Golgi apparatus are organelles called lysosomes.
They contain digestive enzymes, and they are the sites
where macromolecules proteins, polysaccharides, nucleic
acids, and lipids—are hydrolyzed into their monomers.
Lysosomes are about 1 μm in diameter, are surrounded by a
single membrane, and have a densely staining, featureless
interior. There may be dozens of lysosomes in a cell,
depending on its needs.
Lysosomes are sites for the breakdown of food and foreign
objects taken up by the cell. These materials get into the
cell by a process called phagocytosis (phago-, “eating”;
cytosis, “cellular”), in which a pocket forms in the
plasma membrane and eventually deepens and encloses
material from outside the cell. This pocket becomes a
small vesicle that breaks free of the plasma membrane to
move into the cytoplasm as a phagosome containing food or
other material. The phagosome fuses with a primary
lysosome, forming a secondary lysosome where digestion