plant versus animal cell
/ plant VER-sus AN-ih-mul SELL /
Plants and animals are both made of eukaryotic cells, so under a microscope they share most of the same machinery — nucleus, mitochondria, ER, Golgi, ribosomes. But a handful of differences immediately give away which is which, and those differences flow directly from the very different lives the two kingdoms lead.
The signature features of a plant cell that an animal cell lacks are: a rigid cellulose cell wall outside the membrane, one or more chloroplasts for making food from sunlight, and a large central vacuole that fills most of the cell and provides turgor pressure. Plant cells also tend to have a fixed, boxy shape. Animal cells, by contrast, have no wall (so they are flexible and varied in shape), no chloroplasts (they must eat to get energy), only small vacuoles, and they have centrioles plus, often, lysosomes that are more prominent than in plants.
The logic behind the list is worth seeing: plants are stationary and feed themselves with light, so they need a wall and chloroplasts and a water-pressure skeleton; animals move and hunt, so they trade the rigid wall for flexibility. Fungal cells add yet another variation — a wall made of chitin rather than cellulose, and no chloroplasts — a reminder that "plant vs animal" is a useful starting contrast, not the whole story of cellular diversity.
In a classic biology lab, you can tell an onion-skin cell from a cheek cell at a glance: the onion cell has straight, boxy walls; the cheek cell is a soft, rounded blob.
Boxy and rigid says plant; soft and round says animal.
Both cell types have mitochondria — a plant cell is not "powered only by chloroplasts." Plants still need mitochondria to spend the energy stored in the sugar their chloroplasts make.