BiologyCLASS 10CBSE
answered 25 May 2026What are cells? What is their structure? What are different types of cells and organelles?
A.VERIFIED ANSWERfact-checked by tutors
A cell is the smallest structural and functional unit of all living organisms. Robert Hooke first observed cells in 1665 using cork under a microscope.
Two fundamental cell types:
| Feature | Prokaryotic | Eukaryotic |
|---|---|---|
| Nucleus | No membrane-bound nucleus | Has a true nucleus |
| Size | 1–10 micrometers | 10–100 micrometers |
| Organisms | Bacteria, Archaea | Plants, Animals, Fungi, Protists |
Organelles of a typical eukaryotic (animal) cell:
| Organelle | Function |
|---|---|
| Cell membrane | Controls what enters and exits the cell |
| Nucleus | Contains DNA; control center of the cell |
| Mitochondria | Generates ATP (energy), "powerhouse of the cell" |
| Ribosomes | Build (synthesize) proteins |
| Rough ER | Processes and transports proteins; covered with ribosomes |
| Smooth ER | Synthesizes lipids; detoxifies chemicals |
| Golgi Apparatus | Packages and ships proteins and lipids, "post office of the cell" |
| Lysosomes | Digest waste, worn-out organelles, and foreign material |
| Cytoplasm | Jelly-like fluid filling the cell, medium for chemical reactions |
| Cytoskeleton | Protein framework giving the cell shape and enabling movement |
| Vacuoles | Storage small in animal cells, large central vacuole in plant cells |
Additional plant cell structures:
- Cell wall rigid cellulose outer layer, structure and protection
- Chloroplasts contain chlorophyll, site of photosynthesis; "kitchen of the cell"
- Large central vacuole stores water and maintains turgor pressure
Specialized human cell types: Red blood cells (oxygen transport), neurons (electrical signals), muscle cells (contraction), sperm and egg cells (reproduction)