Plant and animal cell comparison

Plant and animal cells share several structures that carry out the same basic activities. A typical plant cell also has structures that support it and enable photosynthesis.

Structures shared by plant and animal cells

• The cell membrane controls the movement of substances into and out of the cell.
• The cytoplasm is where many chemical reactions occur.
• The nucleus contains genetic material and controls the activities of the cell.
• Ribosomes make proteins.
• Mitochondria are the sites of aerobic respiration, which releases energy for the cell.

Structures of a typical plant cell

A typical plant cell has three additional structures:

• The cell wall lies outside the cell membrane. It supports the cell and helps maintain its shape.
• Chloroplasts absorb light for photosynthesis.
• A large vacuole contains cell sap and helps keep the cell firm.

Animal cells do not have a cell wall or chloroplasts. Not every plant cell contains chloroplasts, but in diagrams and images, the combination of a cell wall, chloroplasts and a large vacuole identifies a typical plant cell. The shared structures can be identified in both plant and animal cells.

Bacterial cell structure

A bacterial cell has an outer cell wall surrounding a cell membrane. Inside the membrane are the cytoplasm, ribosomes and genetic material. Unlike a cell with a nucleus, a bacterial cell has its main DNA in the cytoplasm, not enclosed inside a nucleus.

Bacterial cell structures and their functions

• Cell wall: supports and protects the cell. In a diagram, it forms the outer layer around the cell membrane.
• Cell membrane: controls the movement of substances into and out of the cell. It lies just inside the cell wall.
• Cytoplasm: the material filling the inside of the cell, where many chemical reactions occur.
• Ribosomes: small structures in the cytoplasm that make proteins. They are often shown as dots in diagrams.

Bacterial DNA and plasmids

The bacterium’s main genetic material is circular DNA in the cytoplasm. In a diagram, it is often drawn as a large loop, which may appear tangled or folded.

Some bacterial cells also contain plasmids: smaller circles of DNA separate from the main circular DNA. In a diagram, these can be recognised as small loops in the cytoplasm. Plasmids are not present in every bacterial cell.