Chapter 7 Section 1

Cells

The Cell Theory

• The Cell Theory states that all organisms are composed of similar units of organization called cells.

Development of Cell Theory

• Theodore Schwann and Matthias Schleiden are credited with the Cell Theory

The Cell Theory  1. All known living things are made up

of cells.

2. The cell is structural & functional unit of all living things.

3. All cells come from pre-existing cells by division.(No spontaneous generation ).

Microscopes

• The Cell Theory would not exist if it wasn’t for the development of the microscope and the work of others.

Robert Hooke

• In 1663 Robert Hooke discovered cells in a piece of cork, and coined the word CELL.

Van Leeuwenhoek

Anton van Leeuwenhoek used his single lens microscopes and was the first person to observe bacteria and protozoa.

Types of Microscopes

• Compound light microscope

• Electron Microscope

–SEM

–TEM

–STM

Compound Light Microscope

• Can magnify object up to 1500X

• This is an onion cell at 1000x magnification.

Electron Microscope

• Uses electron beams to magnify structures up to 500 000 times.

• Structures inside of the cell can be seen with electron microscope.

• SEM, TEM and STM

Scanning Electron Microscope• Scan the surface of cell to see its 3 D shape.

Transmission Electron Microscope• Can see inside a cell and the organelles

Scanning Tunneling Microscope• Can image atoms on the surface of a molecule.

Compound Light Microscope

• Ocular lens (eyepiece) times objective lens give total magnification

Two Basic Cell Types

• Prokaryotic Cells Mainly single celled organisms

• Eukaryotic Cells Mainly multicellular organisms, although some are single celled (amoeba,algae, yeast)

Prokaryotic Cell

• Prokaryotes have no membrane bound organelles.

• Example – bacteria cell

Eukaryotic Cells

• Eukaryotes – contain membrane bound organelles

• Example – plant and animal cells

Organelles• An organelle is a small

specialized structure inside of a cell.

• An example of an organelle is the nucleus which controls cell functions.