1. The Discovery of the Cell Advancements in technology have allowed scientists to study cells since the 1600s. Pioneer scientists in the study of cells: –Robert Hooke –Matthias Schleiden –Theodor Schwann –Rudolph Virchow – Lynn Margulis

3. Important Scientists Hooke – looked at cork under the microscope; observed empty structures and called them cells. (1665) Schleiden – all plants are made of cells. (1838) Schwann – all animals are made of cells. (1839) Virchow – all living things come from other living things. (1855) Margulis – organelles within some cells were once free-living cells themselves. (1970)

4. The Discovery of the Cell The Cell Theory – fundamental concept in biology; It states: 1.All living things are composed of cells. 2.Cells are the basic units of structure and function in living things. -cells are the building blocks for organisms -all life processes occur in cells 3. New cells are produced from existing cells.

5. Prokaryotes Vs. Eukaryotes Despite their differences, all cells have 2 things in common: 1.Cell (plasma) Membrane 2.DNA Cells can be separated into 2 categories: 1.Prokaryotes – have genetic material that is NOT contained by a nucleus 2.Eukaryotes – have genetic material that is contained by a nucleus

6. Prokaryotes Vs. Eukaryotes Prokaryotes –Small, simple –Lack a nucleus –Lack organization –unicellular Ex. bacteria Eukaryotes –Large, complex –Contain a nucleus –Contain dozens of internal structures –Can be single or multicellular Ex. Plants, animals, fungi, protists.

7. Cell Structure

8. Plant Cell

9. Animal Cell

10. Bacteria Cell

11. Eukaryotic Cell Structure A.Boundary Membranes: 1. Cell Wall -in plant cells only -for support & protection -composed primarily of cellulose (polysaccharide – fiber)

12. A.Boundary Membranes (cont.) 2. Cell (Plasma) Membrane - “gatekeeper” -controls who or what gets in & out of a cell -composed of phospholipids & proteins

13. Cell Membrane Structure