Endomembrane system: lysosomes and vacuoles

Lysosomes are membrane-bound vesicles formed through packaging in the Golgi apparatus.

Lysosomal vesicles, when isolated, carry nearly every type of hydrolytic enzyme (lipases, proteases, carbohydrases and so on), all most active at acidic pH.

These enzymes can digest carbohydrates, proteins, lipids and nucleic acids.

A vacuole is a membrane-enclosed space in the cytoplasm; it stores water and sap along with excretory products and other substances the cell has no use for.

Its single membrane is called the tonoplast. In plant cells the vacuole can take up as much as 90 per cent of the cell volume.

The tonoplast moves several ions and other materials into the vacuole against their concentration gradient, so their concentration inside is much higher than in the cytoplasm.

In Amoeba the contractile vacuole handles osmoregulation and excretion. In many cells, protists for example, food vacuoles form when food particles are engulfed.