Cell Discovery and Theory

History of the Cell Theory

1665- Robert Hooke- made a simple microscope and looked at a piece of cork.

He saw small, box-shaped structures. He called them cellulae (Latin for small rooms). The term cell came from this word.

Late 1600s- Anton van Leeuwenhoek, inspired by Hooke, designed his own microscope.

1838- Matthias Schleiden- studied plant tissues and concluded that all plants are composed of cells.

1839- Theodor Schwann- reported that animal tissues also consist of individual cells.

1855- Rudolph Virchow- proposed that all cells are produced from the division of existing cells.

The conclusions of these scientists and others are summarized as the cell theory.

Cell Theory includes 3 principles.

1. All living organisms are composed of one of more cells.

2. Cells are the basic unit of structure and organization of all living organisms.

3. Cells arise only from previously existing cells, with cells passing copies of their genetic material on to their daughter cells.

Microscope Technology

Compound Light Microscope- consist of glass lenses each magnifies 10 times. The maximum magnifciation without blurring is 1000 X.

Electron Microscopes

Transmission electron microscope (TEM)-uses magnets to aim a bean of electrons at thin slices of cells.

Scanning electron microscope (SEM)- a modified electron microscope that directs electrons over the surface of the specimen, producing a 3D image.

Basic Cell Types

Cell- basic structural and functional unit of all living organisms.

Cells are grouped in 2 categories1. Eukaryotic Cells-

-eu prefix from Greek, meaning true-kary from Greek, meaning nucleus

2. Prokaryotic Cells-pro prefix from Greek, meaning before

Eukaryotic Cell Prokaryotic CellNucleus- a distinct central organelle that contains the cell's genetic material (DNA)

Organelles-Specialized structures that carry out specific cell functions.

Organisms that are made up of eukaryotic cells are called eukaryotes.

Plasma Membrane-Special boundary that helps control what enters and leaves the cell.

Has no nucleus or organelles.

Organisms that are made up of prokaryotic cells are called prokaryotes. This includes most unicellular organisms like bacteria.