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

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)

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.

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

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.

Cell Structure

Plant Cell

Animal Cell

Bacteria Cell

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

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

Cell Membrane Structure