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← 🌱 Biology · usually met in Std 6-12

The cell

The smallest unit that is alive. Everything living is one cell, or a community of them working as one body.

Animal cell nucleus (DNA) mitochondrion membrane ribosomes Plant cell large vacuole cell wall (rigid) chloroplasts — where photosynthesis happens nucleus
Drawn for Star Student.
Onion cells under a light microscope
Kateryna Kot · CC BY-SA 4.0 ↗ · where it came from ↗

A cell is bounded by a membrane that decides what goes in and out. Inside is cytoplasm, and in most cells a nucleus holding the DNA. Mitochondria release energy from food. Ribosomes build proteins. Plant cells add a rigid cell wall, a large water-filled vacuole, and chloroplasts for photosynthesis — which is the whole difference between something that must find food and something that makes its own.

Cells come in two broad kinds. Prokaryotes, such as bacteria, have no nucleus and keep their DNA loose in the cell. Eukaryotes — plants, animals, fungi, and single-celled organisms like amoeba — keep it packaged in a nucleus and have specialised compartments. Every cell in your body came from the division of an earlier cell, in an unbroken line going back to the first cells on Earth.

Worth knowing

  • Robert Hooke named them in 1665, after the small rooms monks lived in, when he looked at cork through a microscope.
  • An adult human is made of tens of trillions of cells, of a few hundred different types.
  • Your body also carries roughly as many bacterial cells as human ones, mostly in the gut, mostly useful.

Want to see it moving? Search YouTube for “The cell” ↗ — we send you to the search rather than to one video, because a link to one video eventually rots.

See also

🌱 DNA🌱 Photosynthesis🌱 Respiration

🧭 Do not take our word for it

This entry was written for Star Student in our own words — it is a summary, not a source. Here is where the people who actually hold these facts keep them. Go and check.

Your own textbook ↗Balbharati publishes the textbooks free to read online. Your chapter is the thing to check first — an encyclopedia is a summary, and the syllabus is the syllabus. Zoological Survey of India ↗India's animal life, surveyed and catalogued since 1916.

Last gone through: 1 October 2026 · How these entries are written

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