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 & outof a cell

-composed of phospholipids& proteins

Cell Membrane Structure