onion peel cells

Onion peel cells are the plant cells you see when you observe the thin, transparent skin peeled from an onion bulb under a microscope.

• They form a single layer of tightly packed cells, so under the microscope they look like neat rectangular “brick-like” boxes arranged side by side.
• They are a favourite for beginners because the peel is easy to remove, very thin (light can pass through), and the cells are large enough to be seen clearly.
• Each onion peel cell has a cell wall on the outside, which gives the cell a fixed shape and strength—this is why the “brick” outlines look so clear.
• Inside the wall is the cell membrane, and then the cytoplasm with a nucleus; these parts show that plant and animal cells share the same basic plan.
• A large vacuole is usually present and helps the cell stay firm (like an air-filled cushion keeping a ball in shape).
• Even though onion is a plant, onion peel cells usually do not show green chloroplasts because the bulb grows underground and does not photosynthesise much.

Seeing onion peel cells makes it easier to understand that living things are built from organised, repeating units—cells—with parts that each do a specific job.