Cells: Cell Structure And Function
1.1 Cell Structure And Function
Cell Theory
- All living things made of cells.
- Cell = basic unit of life.
- New cells come from pre-existing cells.
Types Of Cells
| Type | Key Features | Examples |
|---|---|---|
| Animal | No cell wall, no chloroplast, small vacuoles | Human cheek cell |
| Plant | Cell wall (cellulose), chloroplasts, large vacuole | Leaf palisade cell |
| Bacterial | Cell wall (not cellulose), circular DNA, plasmids, no nucleus | E. coli |
Cell Structures & Functions
| Structure | Function | Found In |
|---|---|---|
| Cell membrane | Controls movement of substances | All cells |
| Cytoplasm | Site of metabolic reactions | All cells |
| Nucleus | Contains DNA, controls activities | Plant & animal |
| Mitochondria | Aerobic respiration → energy | Plant & animal |
| Ribosomes | Protein synthesis | All cells |
| Chloroplasts | Photosynthesis (chlorophyll) | Plant only |
| Vacuole | Storage, support (turgor pressure) | Large in plant cells |
| Cell wall | Support, protection, shape | Plant & bacterial cells |
Bacterial Cell Structure
- DNA: Circular, not in nucleus.
- Plasmids: Extra small DNA loops.
- Ribosomes: Smaller than in plants/animals.
- Cell membrane + wall: Protection + structure.
Key Functions
- Plant cells photosynthesise; animals don’t.
- Bacterial cells reproduce quickly, no true nucleus.
- Specialised organelles make cell efficient.
Quick Tip:
- Plant cell = “boxy, green parts, big vacuole”.
- Animal cell = “roundish, no green parts”.
- Bacterial cell = “tiny, no nucleus, DNA loop”.