4.1—Plant cell structure and ultrastructure

Plant cells share the core eukaryotic organelles but also contain structures specialised for a cell wall, photosynthesis, storage and communication between neighbouring cells.

The cellulose cell wall and middle lamella support and join cells. Plasmodesmata connect cytoplasm; pits are thin wall regions that aid transport. Chloroplasts contain thylakoid membranes and stroma for photosynthesis, amyloplasts store starch, and the vacuole is enclosed by a selective tonoplast and contains cell sap.

Water pressure against the vacuole makes a cell turgid, while cellulose and the middle lamella stop the surrounding wall from collapsing. A chloroplast is therefore not simply a “plant mitochondrion”: its compartments support photosynthesis.

Not every plant cell contains chloroplasts, and the tonoplast surrounds the vacuole rather than the whole cell. Compare the extra plant structures with the shared animal-cell organelles.