Prokaryotic: very small, no nucleus, no internal structures

Eukaryotic: bigger, well defined nucleus, many membrane bound organelles

1. Archaea : bacteria-like cells that are metabolically adaptable to harsh environments (halophiles, thermophiles, methanogens)
2. Bateria: variety of bacteria including most "typical" groups

• metabollically diverse
• assimilate soluble substrates which are either soluble initially or have been solubilized by exocellular enzymes
• live in anaerobic and aerobic environments
• key component of the decomposers of o matter

1. Requirements of Cells

• Energy
• Carbon
• Reducing Equivalents

2.      Prokaryotic organisms by metabolic requirements

• Cell Carbon : autotrophic (inorganic carbon CO₂) and heterotrophic ( organic carbon)
• Energy : phototrophic (light) , chemotrophic (oxidation of e^- donors) , chemolithotrophs (oxidize inorganics) , chemoorganotrophs (oxidize organics)

All cells need...

1. Capture and excretion of nutrients and waste products
2. Protection from environment
3.  Metabolic conversion of nutrients
4. Preservation and replication of genetic info

• all chemical processes taking place in the cell
• chemicals from which cells are built are called nutrients
• metabolism generates the essential elements of the cell and the E to put them together in an organized fashion