KEY CONCEPT Cells are the Basic unit of life.

1. KEY CONCEPT Cells are the Basic unit of life.

2. The cell theory grew out of the work of many scientists and improvements in the microscope. • Many scientists contributed to the cell theory. Wacky History of Cells

3. 1665: Hooke was the first to identify cells, and he named them. • Hooke Fig. Hooke observed the cell walls of dead plant cells

4. The cell theory grew out of the work of many scientists and improvements in the microscope. • Many scientists contributed to the cell theory. • More was learned about cells as microscopes improved. • The cell theory is a unifying concept of biology. Fig. Leeuwenhoek observed and drew microscopic life, which he called animalcules, in pond water

5. 1838: Schleiden was the first to note that plants are made of cells.1839: Schwann concluded that all living things are made of cells.1855: Virchow proposed that all cells come from other cells. • Schleiden, Schwann and Virchow

6. Early studies led to the development of the cell theory. • The Cell theory has three principles. 1. All organisms are made of cells.

7. Early studies led to the development of the cell theory. • The Cell theory has three principles. 2. All existing cells are produced by other living cells.

8. Early studies led to the development of the cell theory. • The Cell theory has three principles. 3. The cell is the most basic unit of life. Summarize: Explain the 3 major principles of cell theory in your own words. Explain what it means to be a theory.

9. All cells share certain characteristics. • Cells tend to be microscopic. • All cells are enclosed by a membrane. • All cells are filled with cytoplasm. • Have DNA/RNA Ex: bacteria cell Top: animal cell Left: plant cell

10. nucleus organelles cell membrane • There are two cell types: eukaryotic cells and prokaryotic cells. • Eukaryotic cells have a nucleus and other membrane bound organelles like mitochondria or ER • Example: protist cells, plant cells, animal cells, fungi cells

11. cytoplasm • Prokaryotic cellslack a nucleus and most internal structures of eukaryotic cells. • Prokaryotic cells do not have membrane bound organelles. No mitochondria, chloroplast, ER, etc… • All reactions in a prokaryotic cell take place in the cytoplasm of the cell. cell membrane • Prokaryotes are a lot smaller in size compared to eukaryotes. Figure: In prokaryotic cells, such as a bacterium (above), DNA is suspended in the cytoplasm. In eukaryotic cells, the nuclear envelope separates DNA from the cytoplasm. Summarize:What characteristics are shared by most cells? Differentiate between eukaryotes and prokaryotes.