Cell | Definition, Types, Functions, Diagram, Division, Theory,
Oct 31, 2024 · 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 …
Human body | Organs, Systems, Structure, Diagram, & Facts
Oct 28, 2024 · The human body consists of trillions of cells, each capable of growth, metabolism, response to stimuli, and, with some exceptions, reproduction. Although there are some 200 different types of cells in the body, these can be grouped into four basic classes.
Structure and types of cells | Britannica - Encyclopedia Britannica
A single cell can be a complete organism in itself, as in bacteria and protozoans. Groups of specialized cells are organized into tissues and organs in multicellular organisms such as higher plants and animals. There are two distinct types of cells: prokaryotic cells and eukaryotic cells.
Biology | Definition, History, Concepts, Branches, & Facts | Britannica
Oct 21, 2024 · Cell biology is the study of cells—the fundamental units of structure and function in living organisms. Cells were first observed in the 17th century, when the compound microscope was invented.
Stem cell | Definition, Types, Uses, Research, & Facts | Britannica
Oct 31, 2024 · Stem cell, an undifferentiated cell that can divide to produce some offspring cells that continue as stem cells and some cells that are destined to differentiate (become specialized).
Cell membrane | Definition, Function, & Structure | Britannica
Sep 29, 2024 · Cell membrane, thin membrane that surrounds every living cell. The cell membrane functions as a barrier, keeping cell constituents in and unwanted substances out, and as a gate, allowing transport into the cell of essential nutrients and movement from the cell of waste products.
Cell theory | Definition, History, Importance, Scientists, First ...
Oct 24, 2024 · Cell theory, fundamental scientific theory of biology according to which cells are held to be the basic units of all living tissues. First proposed by German scientists Theodor Schwann and Matthias Jakob Schleiden in 1838, the theory that all plants and animals are made up of cells marked a great.
cell - Kids | Britannica Kids | Homework Help
The cell is the smallest unit with the basic properties of life. Some tiny organisms, such as bacteria and yeast, consist of only one cell. Large plants and animals have many billions of cells. Human beings are made up of more than 75 trillion cells. The study of cells is a branch of biology.
Human genetics | Description, Chromosomes, & Inheritance
Human genetics, study of the inheritance of characteristics by children from parents. Human inheritance does not differ in any fundamental way from inheritance in other organisms. An understanding of human heredity is important in the prediction, diagnosis, and treatment of diseases that have a genetic component.
Cell - Structure, Organelles, Metabolism | Britannica
Oct 31, 2024 · Cell - Structure, Organelles, Metabolism: Like the cell membrane, membranes of some organelles contain transport proteins, or permeases, that allow chemical communication between organelles.