CELL STRUCTURE & FUNCTION

Plant cells possess an extracellular, rigid cell wall made primarily of cellulose that protects the cell from mechanical stress and osmotic lysis.

Cellulose is a linear polymer of β-D-glucose units that organizes into microfibrils to give the plant cell wall its high tensile strength.

Mature plant cells feature a massive central vacuole that maintains turgor pressure, whereas animal cells contain multiple small, transient vacuoles.

The tonoplast is the specialized semi-permeable membrane enclosing the plant vacuole, containing active transport pumps to maintain cell turgidity.

Chloroplasts are specialized green plastids containing chlorophyll pigments that execute the light and dark reactions of photosynthesis in plants.