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Most cells are only visible under a microscope. Cells emerged on Earth about 4 billion years ago. All cells are capable of replication, protein synthesis, and motility. Cells are broadly categorized into two types: eukaryotic cells, which possess a nucleus, and prokaryotic cells, which lack a nucleus but have a nucleoid region.
Cellular compartments in cell biology comprise all of the closed parts within the cytosol of a eukaryotic cell, usually surrounded by a single or double lipid layer membrane. These compartments are often, but not always, defined as membrane-bound organelles. The formation of cellular compartments is called compartmentalization.
Eukaryotic cells are some 10,000 times larger than prokaryotic cells by volume, have their DNA organised in a nucleus, and contain membrane-bound organelles. [ 54 ] The division between prokaryotes and eukaryotes has been considered the most important distinction or difference among organisms.
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.
Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. [1] [2] All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living and functioning of organisms. [3] Cell biology is the study of the structural and functional ...
Sarcina cells, for example, are arranged in cubical pockets because cell division alternates regularly among the three perpendicular planes. Streptococcus spp. resemble a string of beads because division always occurs in the same plane. Some of these strings, for example, S. pneumoniae, are only two cells long.
The reason that I diagramed the prokayotic bactrial cell is they are the most familiar ones. In my opinion, this image can indicate the general prokaryotic cell but I changed the description of that. Since this image supposed to show a general prokaryotic bacterial cell, the nucleoid has been truely shown. Thank you for the notice.
This glossary of biology terms is a list of definitions of fundamental terms and concepts used in biology, the study of life and of living organisms.It is intended as introductory material for novices; for more specific and technical definitions from sub-disciplines and related fields, see Glossary of cell biology, Glossary of genetics, Glossary of evolutionary biology, Glossary of ecology ...