Safekipedia

Cell (biology)

Explorer · ages 7 and underAdapted from Wikipedia
A diagram of an animal cell, showing the tiny parts that work together inside it, such as the nucleus and mitochondria.

What is a cell?

A cell is the smallest basic unit that makes up all living things. The word comes from a Latin word that means "small room." Most cells are too small to see without a microscope.

Each cell has a cell membrane around the outside. Inside is a jelly-like part called cytoplasm, which holds the genetic material. Some cells can even move on their own.

Two big groups

Living things are sorted into two groups, prokaryotes and eukaryotes. Prokaryotes are always single-celled, and they include bacteria. Eukaryotes can be single-celled or many-celled. Many-celled eukaryotes include animals and plants.

Eukaryotic cells have a nucleus with a membrane around it. Plant cells have chloroplasts, which help them make sugars using photosynthesis.

Who found cells?

In 1665, Robert Hooke looked at a thin slice of cork under his microscope. He saw small boxes that reminded him of the small rooms in a monastery. That is how cells got their name.

Later, Matthias Jakob Schleiden and Theodor Schwann showed that plants and animals are both made of cells. Scientists still learn new things about cells today.

Quiz time!

3 questions about Cell (biology)

Question 1 of 3

What is the smallest basic unit that makes up all living things?

Pictures

A display showing the structure of an animal cell at the Indian Museum in Kolkata, India.
A diagram showing how chemical changes to proteins called post-translational modifications play a role as cells develop into their specialized types.
A diagram showing the three germ layers that form early in the development of an embryo, and the body parts each layer later becomes.
A diagram showing the different types of cells that develop from the three germ layers in an early embryo.
A drawing of onion root-tip cells under a microscope, showing different stages of cell division, from resting cells to dividing cells and newly formed pairs of daughter cells.
A microscope image of the tiny worm Caenorhabditis elegans, with special stains that make its body parts glow under fluorescent light.
An engraving from Robert Hooke's 1665 book Micrographia, showing tiny cork cells and mimosa leaves as seen through an early microscope.
HeLa cells, a common type of human cell grown in laboratories, shown under a microscope after being stained with a blue fluorescent dye that makes the cell nuclei glow.
Stromatolites are layered rock formations built by ancient microbes. These examples, about one billion years old, are preserved in the Siyeh rock formation in Glacier National Park, Montana.
Structure of a typical bacterial cell, generally similar to the archaeal cell structure. The bacterial flagellum shown, differs from the archaellum in archaea
Bacteria and archaea divide by binary fission
Prokaryotes divide by binary fission, while eukaryotes divide by mitosis or meiosis.
In the theory of symbiogenesis, a merger of an archaean and an aerobic bacterium created the eukaryotes, with aerobic mitochondria, some 2.2 billion years ago. A second merger, 1.6 billion years ago, added chloroplasts, creating the green plants.

Keep exploring

Latin
Eukaryote
Bacteria
Animal
Cell nucleus
Photosynthesis

This article is a child-friendly adaptation of the Wikipedia article on Cell (biology), available under CC BY-SA 4.0.

Images from Wikimedia Commons. Tap any image to view credits and license.