Animal Cell Ultrastructure

Wikimedia Commons: Animal cell showing nucleus, rough ER, smooth ER, Golgi apparatus, mitochondria, lysosomes, ribosomes, and centrioles.

Key structures to identify in animal cell:

1. Nucleus — double membrane + nucleolus + chromatin
2. Rough ER — studded with ribosomes
3. Smooth ER — no ribosomes
4. Golgi apparatus — stacked cisternae, cis and trans faces
5. Mitochondria — double membrane + cristae
6. Lysosomes — small, dark, round vesicles
7. Ribosomes — small granules (80S in cytoplasm)
8. Centrioles — near nucleus, microtubule cylinders
9. Plasma membrane — fluid mosaic structure

Plant Cell Ultrastructure

Wikimedia Commons: Plant cell showing cell wall, chloroplasts, central vacuole, plastids, and plasmodesmata.

Key structures unique to plant cell (absent in animal):

1. Cell wall — outer rigid layer (cellulose)
2. Middle lamella — between adjacent cells (calcium pectate)
3. Chloroplasts — green organelles, double membrane, grana
4. Central vacuole — large, bounded by tonoplast
5. Plasmodesmata — cytoplasmic channels through cell wall
6. No centrioles (in most higher plants)
7. No lysosomes (vacuole performs digestive function)

Identification Tips for NEET Diagrams

• Mitochondria = double membrane + cristae (inner folds) → distinguish from chloroplast (double membrane + thylakoid stacks)
• Golgi = stacked flat cisternae with vesicles on both ends
• Nucleus = double membrane + dark nucleolus inside
• Rough ER = membrane studded with dots (ribosomes)