Cell: The Unit of Life is a 2–3 question chapter in NEET and the base for genetics and biotechnology. NCERT lines are asked directly, so read these notes with the textbook.
Cell theory
- Schleiden and Schwann (1838–39); Virchow added ‘Omnis cellula-e cellula’ (cells arise from pre-existing cells).
- Smallest cell: Mycoplasma (0.3 μm); largest: ostrich egg; longest: nerve cell.
Prokaryote vs eukaryote
| Feature | Prokaryote | Eukaryote |
|---|---|---|
| Nucleus | No membrane; nucleoid | True nucleus |
| Ribosome | 70S | 80S (70S in mitochondria/chloroplast) |
| Membrane-bound organelles | Absent | Present |
| Cell wall | Peptidoglycan (bacteria) | Cellulose (plant), chitin (fungi) |
| Plasmids | Present | Rare |
Organelles
| Organelle | Key point | Function |
|---|---|---|
| Mitochondria | Double membrane, cristae, own DNA | ATP synthesis |
| Chloroplast | Thylakoids, grana, stroma | Photosynthesis |
| ER | Rough (ribosomes) / smooth | Protein / lipid synthesis |
| Golgi | Cis and trans faces | Packaging, glycosylation |
| Lysosome | Hydrolytic enzymes | Digestion (‘suicide bags’) |
| Ribosome | rRNA + protein, no membrane | Protein synthesis |
| Centrosome | Two centrioles (9 + 0) | Spindle formation |
| Cilia/flagella | 9 + 2 axoneme | Movement |
| Nucleus | Nuclear pores, nucleolus | Control, rRNA synthesis |
| Vacuole | Tonoplast (plants) | Storage, turgor |
NEET quick facts
- Fluid mosaic model: Singer and Nicolson (1972); phospholipids + proteins (52% protein in RBC membrane)
- Chromosome types by centromere: metacentric, submetacentric, acrocentric, telocentric
- Plant cell lacks centrioles; animal cell lacks cell wall and plastids
- Microbodies (peroxisomes) contain catalase
Common mistakes
- Mixing 9 + 2 (cilia) with 9 + 0 (centriole)
- Saying prokaryotes lack ribosomes — they have 70S
- Forgetting mitochondria and chloroplasts are semi-autonomous
Related: Digestive system NEET notes.
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Frequently asked questions
Is this Cell content at JEE/NEET level?
Yes. It covers the formulas, facts and question types that appear in JEE Main, JEE Advanced and NEET, with the NCERT base that these exams follow.
How many questions come from Cell?
Typically one to three questions per paper, depending on the year. Check the chapter-wise weightage post and give this topic time in proportion.
Where can I get cell the unit of life doubts solved quickly?
On DoubtPay AI you can type or photograph a module or mock-test question, select JEE or NEET, and get a step-by-step solution, a hint, or a check of your own attempt in seconds. ₹49 gives 100 answers with no subscription.
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