Prokaryotic Cells  Basic cell that does not have a membrane-bound nucleus  DNA – spread through much of cell  Size – very small  Organization – always single celled  Organelles – only one type of organelle

Prokaryotic Cells  Bacteria  Archaea

Eukaryotic Cells  Complex cell that has a nucleus surrounded by a membrane  DNA – within nucleus  Size – much larger than prokaryotic  Organization – sometimes unicellular, often multicellular  Organelles – many types of organelles

Eukaryotic Cells  Protists  Fungi  Plants  Animals

Unicellular Organisms  Some prokaryotes Examples: bacteria and archaea Some Eukaryotes Examples: algae, fungus, amoeba

Unicellular Organisms  Made up of one cell  Processes needed for survival are carried out within one cell

Multicellular Organisms  Only contain eukaryotic cells  Made of more than one cell  Each type of cell has a specific job that is important to the survival of the organism

Cell Differentiation  Process by which one type of cell becomes a different type of cell – starts with unspecialized cells

Differentiation in Plants  Unspecialized cells in plants called meristems  Found in tips of roots and stems  Produce cells with specialized structures and functions which become parts of stems, leaves, flowers or roots.

Differentiation in Animals  Unspecialized cells in animals called stem cells  Lots of stem cells found in embryos – can develop into many types of cells  Some stem cells found in adults : - Stem cells in bone marrow can produce more than a dozen types of blood cells -stem cells in skeletal muscles Copy diagram on p. 281