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Light micrograph of a moss's leaf cells at 400X magnification. The following outline is provided as an overview of and topical guide to cell biology: . Cell biology – A branch of biology that includes study of cells regarding their physiological properties, structure, and function; the organelles they contain; interactions with their environment; and their life cycle, division, and death.
In cell biology, an organelle is a specialized subunit, usually within a cell, that has a specific function. The name organelle comes from the idea that these structures are parts of cells, as organs are to the body , hence organelle, the suffix -elle being a diminutive .
The eukaryotic DNA is organized in one or more linear molecules, called chromosomes, which are associated with histone proteins. All chromosomal DNA is stored in the cell nucleus, separated from the cytoplasm by a membrane. [2] Some eukaryotic organelles such as mitochondria also contain some DNA. Many eukaryotic cells are ciliated with primary ...
The membranes are slightly different from cell to cell and a cell's function determines the size and structure of the ER. [18] Mitochondria: Commonly known as the powerhouse of the cell is a double membrane bound cell organelle. [19] This functions for the production of energy or ATP within the cell.
Prokaryotes have fewer organelles than eukaryotes. Both have plasma membranes and ribosomes (structures that synthesize proteins [ clarification needed ] and float free in cytoplasm ). Two unique characteristics of prokaryotes are fimbriae (finger-like projections on the surface of a cell) and flagella (threadlike structures that aid movement).
Unicellular organisms are thought to be the oldest form of life, with early protocells possibly emerging 3.5–4.1 billion years ago. [1] [2] Although some prokaryotes live in colonies, they are not specialised cells with differing functions. These organisms live together, and each cell must carry out all life processes to survive.
In terms of protein synthesis, the necessary organelles are relatively near one another. The nucleolus within the nuclear envelope is the location of ribosome synthesis. The destination of synthesized ribosomes for protein translation is rough endoplasmic reticulum (rough ER), which is connected to and shares the same membrane with the nucleus.
One cell, with organelles e.g. cilia for specific functions: Yes: Inter-cellular (inter-organismal) signalling [22] Swarming protistan: Dictyostelium (cellular slime mould) Unicellular amoebae: Yes: Free-living unicellular amoebae for most of lifetime; swarm and aggregate to a multicellular slug, cells specialising to form a dead stalk and a ...