Animal and plant cells
All cells are surrounded by a cell membrane that controls what enters and leaves, contain cytoplasm where reactions occur, and (in most cases) a nucleus that controls the cell's activities and contains genetic material. Ribosomes in the cytoplasm make proteins, and mitochondria release energy by aerobic respiration.
Key idea
Structures found in a plant cell but not an animal cell: a cell wall made of cellulose (support and shape), chloroplasts containing chlorophyll (photosynthesis), and a large permanent vacuole filled with cell sap.
Function of the main parts
| Nucleus | controls activities; holds genetic material |
| Mitochondria | site of aerobic respiration (release energy) |
| Chloroplast | absorbs light for photosynthesis |
| Cell wall | cellulose; gives support and shape |
| Vacuole | stores cell sap; keeps cell firm |
Bacterial cells
Bacterial cells have a cell wall, cell membrane, cytoplasm and ribosomes, but no nucleus – their genetic material is a circular loop of DNA free in the cytoplasm. They may also have plasmids.
Remember
- Cell wall is cellulose in plants – not the same as the cell membrane.
- Chloroplasts and a large vacuole are found in plant cells only.
- Bacteria have no true nucleus.