Chapter 5: The Fundamental Unit of Life
5.1 Discovery of the Cell
Robert Hooke first observed cells in a thin slice of cork using a self-designed microscope. He called these boxes 'cells' (Latin for 'little room').
Other vital contributions:
- Leeuwenhoek (1674): Discovered free-living cells in pond water.
- Robert Brown (1831): Discovered the Nucleus.
- Purkinje (1839): Coined the term 'Protoplasm'.
5.2 Structural Organisation
Every cell has three basic features: Plasma Membrane, Nucleus, and Cytoplasm.
Diffusion: Spontaneous movement of particles from high to low concentration.
Osmosis: Diffusion of water through a selectively permeable membrane.
5.3 Cell Organelles
Mitochondria
Known as the Powerhouse of the cell. Generates energy in the form of ATP molecules.
Lysosomes
Called Suicide Bags. Contain powerful digestive enzymes to break down waste/worn-out parts.
Endoplasmic Reticulum
Large network of tubes. RER (Rough) handles protein synthesis; SER (Smooth) handles lipid manufacture.
Golgi Apparatus
Involved in storage, modification, and packaging of products in vesicles.
5.4 Cell Division
| Process | Description | Result |
|---|---|---|
| Mitosis | Division for growth and repair. | 2 Identical daughter cells. |
| Meiosis | Division for reproduction (gametes). | 4 Cells with half chromosomes. |
Chapter Summary
- The cell is the structural and functional unit of life.
- Plant cells differ from animal cells by having a Cell Wall and Plastids.
- Cell organelles perform specialized functions vital for survival.