What is the pH of a lysosome?

(a) Acidic

(b) Basic

(c) Neutral

(d) Depends on the cell type

(a) Acidic

The internal environment of a lysosome is kept acidic, with a pH ranging from approximately 4.5 to 5.0.

This acidic pH is crucial for the lysosome's function. It contains powerful digestive enzymes, known as acid hydrolases, which are designed to work optimally in an acidic environment. The lysosomal membrane actively pumps hydrogen ions (protons) into its interior to maintain this low pH.

This acidity also serves as a safety feature for the cell. If a lysosome were to break and leak its enzymes into the cytoplasm (which has a neutral pH of about 7.2), the enzymes would become much less active, preventing them from destroying the cell.