3.1 Cell Theory KEY CONCEPT Cells are the Basic unit of life.

3.1 Cell Theory Development of Cell Theory Many scientists contributed to the cell theory. 1) 1665 Hooke was 1 st to look at cells 2) 1674 Leeuwenhoek first to look at living cells in pond water 3) 1838 Schleiden studied living plant cells and concluded all plants are made of cells 4) 1839 Schwann after studying animal cells concluded that all animals are made of cells 5) 1855 Virchow concluded all cells come from cells

3.1 Cell Theory Development of Cell Theory The Cell theory has three principles. 1) All organisms are made of cells.

3.1 Cell Theory Development of Cell Theory The Cell theory has three principles. 1) All organisms are made of cells. 2) All existing cells are produced by other living cells.

3.1 Cell Theory Development of Cell Theory. The Cell theory has three principles. 1) All organisms are made of cells. 2) All existing cells are produced by other living cells. 3) The cell is the most basic unit of life. The Cell Theory was the first unifying theory in Biology

3.1 Cell Theory Prokaryotic cells vs eukaryotic cells. All cells share certain characteristics. – –Cells tend to be microscopic. – –All cells are enclosed by a membrane. – –All cells are filled with cytoplasm. Bacterium (colored SEM; magnification 8800x) cell membrane cytoplasm

3.1 Cell Theory Prokaryotic cells vs eukaryotic cells. There are two types of cells

3.1 Cell Theory Prokaryotic cells vs eukaryotic cells. 1) Eukaryotic cells have a nucleus and membrane bound organelles. Nucleus contains DNA Can be single-cellular or multi-cellular nucleus cell membrane

3.1 Cell Theory Prokaryotic cells vs eukaryotic cells. 2) Prokaryotic cells do not have a nucleus. do not have membrane-bound organelles. DNA is in cytoplasm –ALL BACTERIA ARE –PROKARYOTIC!!!! nucleus cell membrane organelles cytoplasm