Unicellular VS. Multicellular Life Unicellular – one-celled organisms Multicellular – organisms that consist of many cells that work together

Unicellular Advantages Self-contained – everything needed for life within single cell Replication can be as simple as the cell copying its DNA and splitting in two Disadvantages Severe limitations on size of organism Small size limits its role

Multicellular Advantages Cell specilaization – cells that do a specific job for organism Greater size – more mobility, easier to catch food, better defense Greater diversity Disadvantages Greater size requires greater resources All cells must reproduce for growth to occur Life requires a cooperative balance between all cells in organism

Cell Specialization Cells in the organism develop in different ways to perform different tasks. EX: Nerve cells have a different function in your body than muscle cells. Root cells in plants do a different job than leaves in plants. EVERY CELL has a complete set of identical DNA. They contain the genetic information for the entire organism.

Levels of Organization Cells Tissues – made up of similar cells Organs – made up of different tissues that work together Organ Systems – A group of organs that work together to perform a specific function

Evolution of Multicellular Life Unicellular organisms live and work together in colonies Colonies, like Volvox, are colonies of individual organisms but they have developed specialized reproductive cells In multicellular organisms, different cells become specialized and must work with other cells to sustain life