Except for some single-celled organisms, such as bacteria and blue green algae, all living cells have a membrane-enclosed nucleus and internal structures called organelles. Most of these are common to both animals and plants. But plant cells have several specialized characteristics.
Surrounding the plasma membrane, the cell wall is a complex structure that provides protection and rigidity, regulates plant growth, and provides a porous medium for distribution of water and nutrients.
Plastids store and synthesize metabolic materials. Chloroplasts convert light into chemical energy, a process called photosynthesis--exclusive to plants.
A large central sac, the vacuole, stores nutrients, waste products and pigments. It also provides structural support for the plant; filled with water, a vacuole may occupy 80 percent or more of the cell and exert significant pressure against the cell wall.
Small tubes called plasmodesmata penetrate cell walls and connect neighboring plant cells, to permit molecules to pass directly from one cell to another.
The tubular network that connects the nucleus to everything else in the cell, the endoplasmic reticulum builds and moves compounds for use inside and outside the cell. It's common to both plants and animals; in plants, however, it also connects cell to cell through the plasmodesmata.