Plant vs Animal Cells: What Each Part Does

Every living thing is made of one or more cells, the smallest units that can carry out the processes of life. New cells only come from existing cells dividing. Most cells are far too small to see without a microscope: a typical plant or animal cell is about 10–100 micrometres across, and a micrometre is a thousandth of a millimetre.

Plants and animals are both made of cells with a nucleus. That shared design is why their cells have so much in common, and why the differences are worth learning.

• Nucleus: holds the cell's DNA and controls its activities.
• Cell membrane: a thin, flexible layer that controls what enters and leaves.
• Cytoplasm: the jelly-like fluid where most of the cell's chemical reactions take place.
• Mitochondria: release energy from glucose by respiration.
• Ribosomes: tiny structures that build proteins. They are too small to see with a school light microscope.

1. Cell wall: a tough layer of cellulose outside the membrane. It supports the cell and gives it a fixed shape.
2. Chloroplasts: contain green chlorophyll and carry out photosynthesis. They are found in the green parts of a plant, such as leaves, not in every plant cell.
3. Large permanent vacuole: filled with cell sap. When full of water it presses outwards on the wall and keeps the cell firm.

Animal cells may have small, temporary vacuoles, but never one large permanent vacuole.

A plant has no skeleton, so it relies on firm cells to hold up its stems and leaves. When water runs short, the vacuoles shrink, the walls are left unsupported and the plant wilts. Chloroplasts let plants make their own food from light, carbon dioxide and water. Animals cannot do this, so they must eat.

Without a rigid wall, animal cells are held in only by their flexible membrane, so they can change shape more easily and are often rounder or irregular.

A classic practical compares a thin layer of onion skin with cells gently scraped from inside the cheek, both stained so the nucleus shows up. Through a school light microscope, which magnifies up to about 400 times:

• The onion cells are box-shaped and sit in neat rows. You can see the outline of each cell wall and a dark, stained nucleus.
• The cheek cells are rounded and irregular, often lying separately. There is no wall, only a thin membrane, and each has a stained nucleus.

Ask students to label only what they can actually see. Ribosomes are far too small to show up at this magnification.

Print it on A4 or US Letter as a handout, or on A3 or Tabloid for the classroom wall. Students can cover one column and test themselves on the other. It pairs with the free LearnBySlides lesson on plant and animal cells, which has speaker notes, a quiz and a worksheet.