The cell is the smallest unit of life. All living things are made of cells. Cell structure and the role of organelles are core biology exam topics.
Discovery of the Cell
The cell was discovered by Robert Hooke in 1665. The cell theory was given by Schleiden and Schwann. Leeuwenhoek first saw living cells.
Types of Cells
- Prokaryotic: no true nucleus (bacteria).
- Eukaryotic: true nucleus (plants, animals).
Important Cell Organelles
- Nucleus: controls cell activities; contains DNA.
- Mitochondria: the powerhouse of the cell.
- Ribosomes: site of protein synthesis.
- Chloroplast: site of photosynthesis (plant cells).
- Lysosomes: called the suicide bags of the cell.
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Plant Cell vs Animal Cell
- Plant cells have a cell wall; animal cells do not.
- Plant cells have chloroplasts; animal cells do not.
- Plant cells have a large central vacuole.
Important Facts
The cell membrane controls what enters and leaves the cell. The nucleus was discovered by Robert Brown. The largest human cell is the ovum and the smallest is the sperm. The longest cell is the nerve cell.
Quick Revision Points
- Cell was discovered by Robert Hooke (1665).
- Mitochondria is the powerhouse of the cell.
- Lysosomes are the suicide bags.
- Plant cells have a cell wall and chloroplasts.
- Nucleus controls all cell activities.
- Bacteria are prokaryotic cells.
- Ribosomes make proteins.