What is cell? explain about cell.?

Class 9 Question

Ànshara Mirza
Jun 30, 2020
The cell (from Latin cella, meaning "small room"[1]) is the basic structural, functional, and biological unit of all known organisms. A cell is the smallest unit of life. Cells are often called the "building blocks of life". The study of cells is called cell biology, cellular biology, or cytology.


Onion (Allium cepa) root cells in different phases of the cell cycle (drawn by E. B. Wilson, 1900)

A eukaryotic cell (left) and prokaryotic cell (right)

IdentifiersMeSHD002477THH1. terminology

[edit on Wikidata]

Cells consist of cytoplasm enclosed within a membrane, which contains many biomolecules such as proteins and nucleic acids.[2] Most plant and animal cells are only visible under a microscope, with dimensions between 1 and 100 micrometres.[3] Organisms can be classified as unicellular (consisting of a single cell such as bacteria) or multicellular(including plants and animals).[4] Most unicellular organisms are classed as microorganisms.

The number of cells in plants and animals varies from species to species; it has been estimated that humans contain somewhere around 40 trillion (4×1013) cells.[a][5] The human brain accounts for around 80 billion of these cells.[6]

Cells were discovered by Robert Hooke in 1665, who named them for their resemblance to cells inhabited by Christian monks in a monastery.[7][8] Cell theory, first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann, states that all organisms are composed of one or more cells, that cells are the fundamental unit of structure and function in all living organisms, and that all cells come from pre-existing cells.[9] Cells emerged on Earth at least 3.5 billion years ago.[

Astha Shukla
Jun 29, 2020
Cell, in biology, the basic membrane-bound unit that contains the fundamental molecules of life and of which all living things are composed. A single cell is often a complete organism in itself, such as a bacterium or yeast. Other cells acquire specialized functions as they mature. These cells cooperate with other specialized cells and become the building blocks of large multicellular organisms, such as humans and other animals. Although cells are much larger than atoms, they are still very small. The smallest known cells are a group of tiny bacteria called mycoplasmas; some of these single-celled organisms are spheres as small as 0.2 μm in diameter (1μm = about 0.000039 inch), with a total mass of 10−14 gram—equal to that of 8,000,000,000 hydrogen atoms. Cells of humans typically have a mass 400,000 times larger than the mass of a single mycoplasma bacterium, but even human cells are only about 20 μm across. It would require a sheet of about 10,000 human cells to cover the head of a pin, and each human organism is composed of more than 30,000,000,000,000 cells.

Swarnava Das
Jan 16, 2021
1.Cell is the basic structural and function unit of life. 
3.Cell was discovered by Robert Hook in 1665 on a piece of cork under a primitive microscope. The cork was a dead cell.
4.Later on, Leuwenhoek discovered a living cell on a pond water.
5.Cells are of two types :- Unicellular and Bicellular.

Kindly please upvote me, if you like my answer.

Sukhmanpreet Kaur
Jun 26, 2020
Cell is the structural and functional unit of life.

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