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Notes E 1.3. Different cells perform various functions. Organisms can be classified by their cell types. Most organisms are unicellular 3 domains of organisms: Archaea : prokaryotes, live in extreme environments
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Notes E 1.3 Different cells perform various functions.
Organisms can be classified by their cell types. • Most organisms are unicellular • 3 domains of organisms: • Archaea: prokaryotes, live in extreme environments • Bacteria: prokaryotes, share some similarities with Archaea, but live in most environments • Eukarya: Eukaryotes, include multicellular organisms (plants, animals, fungi, and some protists)
Domains • Domains, kingdoms, and other classifications remain in flux and debated within the scientific community. • Some scientists recognize 5 kindoms instead of 6. Some refer to domains rather than ingdoms.
Cells in multicellular organisms specialize. • All mc organisms begin as a single fertilized egg cell. • As cells divide, they specialize to perform specific jobs. • The more specialization there is, the more complex the organism is.
A multicellular organism is a community of cells. • Organisms have different levels of organization : • Similar cells group together to form tissues. • Tissues act together to form organs. • Organs and tissues act together to form organ systems.
Scientists use models to study cells. • Scientists use models to make complicated structures or processes easier to understand. • Some examples of models: • Mathematical or chemical equations • Diagrams • Process models • Physical models