Multicellular Life
Levels of Organization
Organism → Organ System → Organ → Tissue → Cell
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Multicellular Organisms: Depend on communication and cooperation between specialized cells
(More than one cell)
Specialized Animal Cells: Nerve Cells, Connective Tissue, Muscle Cells, Blood Cells
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3 Categories of Cells in Mammals
- Stem cells: undifferentiated but can produce specialized cell types or more stem cells.
Two Types
A. Embryonic Stem Cells
B. Adult Stem Cells
- Germ cells: produce gametes (sperm and egg)
- Somatic cells: developed body cells (Muscle, blood, nerve cells,…)
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Cell Specialization: Process of cell development whereby cells develop to perform different tasks
Gene Expression and Cells Specialization/ Differentiation
Cells of an organism have the same DNA, but not all are expressed.
Some genes are turned on and some are turned off
This explains why cells are different.
