Bacteria - Cell Structure, Enzymes, Metabolism | Britannica
Nov 7, 2025 · Bacteria - Cell Structure, Enzymes, Metabolism: The bacterial cell surface (or envelope) can vary considerably in its structure, and it plays a central role in the properties and capabilities of …
Bacteria | Cell, Evolution, & Classification | Britannica
Jan 10, 2026 · Although bacterial cells are much smaller and simpler in structure than eukaryotic cells, the bacteria are an exceedingly diverse group of organisms that differ in size, shape, habitat, and …
Cell | Definition, Types, Functions, Diagram, Division, Theory, & Facts ...
Jan 16, 2026 · What is a cell? A cell is a mass of cytoplasm that is bound externally by a cell membrane. Usually microscopic in size, cells are the smallest structural units of living matter and compose all …
Ribosome | Definition, Function, Formation, Role, Importance, & Facts ...
Jan 16, 2026 · Ribosome, particle that is present in large numbers in all living cells and serves as the site of protein synthesis. Ribosomes occur both as free particles in prokaryotic and eukaryotic cells …
Prokaryote | Definition, Example, & Facts | Britannica
Jan 16, 2026 · All living organisms on Earth are made up of one of two basic types of cells: eukaryotic cells, in which the genetic material is enclosed within a nuclear membrane, or prokaryotic cells, in …
Flagellum | Prokaryotic, Bacterial, Motor Protein | Britannica
Most motile bacteria move by means of flagella. The structures and pattern of movement of prokaryotic and eukaryotic flagella are different. Eukaryotes have one to many flagella, which move in a …
Bacteria - Capsules, Slime, Layers | Britannica
Jan 10, 2026 · Many bacterial cells secrete some extracellular material in the form of a capsule or a slime layer. A slime layer is loosely associated with the bacterium and can be easily washed off, …
Nucleus | Definition, Function, Structure, & Facts | Britannica
Jan 5, 2026 · Nucleus, in biology, a specialized structure occurring in most cells (except bacteria and blue-green algae) and separated from the rest of the cell by a double layer, the nuclear membrane.
Plant cell | Definition, Diagram, Model, Labeled, Characteristics ...
Jan 16, 2026 · Plant cell walls are composed of cellulose, which sets them apart from other organisms with cell walls, such as bacteria (peptidoglycan) and fungi (chitin). Algal cell walls are similar to those …
cell - Students | Britannica Kids | Homework Help
Encyclopædia Britannica, Inc. The smallest unit of living matter that can exist by itself is the cell. Some organisms, such as bacteria, consist of only a single cell. Others, such as large animals and trees, …