Plant and animal cells.

Step 1 of 4

The organelle that catches light

A plant does not eat. It builds its own sugar, from carbon dioxide and water, with the energy of light. That process, photosynthesis, happens in a special organelle our cells do not have.

Kind of cell and Look at are both free.

Step 2 of 4

A plant needs energy too

You have seen the chloroplasts: about a dozen green bodies near the edge of the cell. They work only when there is light. But a plant lives at night too, and in its roots, where light never reaches.

Step 3 of 4

Two membranes

Look closely at a cut chloroplast. Inside are stacks of discs, like coins, holding chlorophyll, the green pigment that catches the light. On the outside an envelope wraps it.

Step 4 of 4

Side by side

Switch Kind of cell between Animal and Plant a few times, and watch what appears and what stays.

The plant cell turns boxy and a little bigger. Outside it a fibrous wall of cellulose appears, as strong as a box. Inside a big central vacuole appears, a bag of water that pushes the rest of the cell out against the wall. When the vacuoles are full, the plant stands up; when they empty, it wilts.