A VIEW OF THE CELLChapter 7

THE DISCOVERY OF CELLS

Objectives Relate advances in microscope technology

to discoveries about cells and cell structure.

Compare the operation of a compound light microscope with that of an electron microscope

Identify the main ideas of the cell theory.

HISTORY OF THE CELL THEORY

With microscopes, scientist were able to identify microorganisms which are made up of Cells!!!!

Cells are the basic units of living organisms

MICROSCOPES

Compound light microscope uses a series of lenses to magnify objects in steps. Magnify up to around 1500times. Allows scientist to observe and illustrate

certain objects.

THE CELL THEORY

Robert Hooke- (English Scientist) by using a compound light microscope, looked and observe dead bark and notice shapes in the bark.

Theodor Schwann- ( German Scientist) looked at animals and saw the same shapes as Hooke.

Therefore the cell theory was made.

THE CELL THEORY

Made up of three main ideas 1. All organisms are composed of one or

more cells.( an organisms can be singled celled or can be multicellular)

2. The cell is the basic unit of structure and organization of an organisms. (very complex but the cell remains the same)

3. All cells come from preexisting cells. (Cell divides to form two identical cells)

ELECTRON MICROSCOPE

1930s-1940s a new microscope developed called the electron microscope.

Electron microscope uses a beam of electrons instead of light to magnify structures up to 500,000 times their actual size.

This allowed scientist to see structures inside the cell.

ELECTRON MICROSCOPE

Two types of electron microscope 1. SEM “Scanning Electron Microscope”-

scan the surfaces of cells to learn their three-dimensional shape.

2. TEM “Transmission Electron Microscope” – allows scientist to study structures contained within a cell.

Coming soon- Scanning tunneling microscope (STM) create computer images of atoms on the surface of molecules.

THE CELL TYPES

Organelles are membrane- bound structures with particular functions within cells.

Prokaryotic cells- are cells that do not contain any membrane-bound organelles. Example- bacteria

Eukaryotic cells- cells that contain membrane- bound organelles. examples- yeast, us!

Robert Brown- observed in the eukaryotic cells contain a prominent structure.

This structure was responsible for cell division. This structure is called the nucleus.Nucleus- central membrane bound organelle

that manages or controls cellular functions.