The Cell Theory The Cell Theory

Some Random Cell Facts The average human being is composed of around 100 Trillion individual cells!!! The average human being is composed of around 100 Trillion individual cells!!! It would take as many as 50 cells to cover the area of a dot on the letter “ i ” It would take as many as 50 cells to cover the area of a dot on the letter “ i ”WOW!!!

EARLY MICROSCOPES Zacharias Janssen - made 1st compound microscope Zacharias Janssen - made 1st compound microscope a Dutch maker of reading glasses a Dutch maker of reading glasses (late 1500’s) (late 1500’s)

Discovery of Cells English Scientist, Robert Hooke, discovered cells while looking at a thin slice of cork through a simple microscope English Scientist, Robert Hooke, discovered cells while looking at a thin slice of cork through a simple microscope. He described the cells as tiny boxes. He described the cells as tiny boxes.

Anton van Leuwenhoek Used a handmade microscope to observe pond scum & discovered single-celled organisms Used a handmade microscope to observe pond scum & discovered single-celled organisms He called them “animalcules” He called them “animalcules” He also observed blood cells from fish, birds, frogs, dogs, and humans He also observed blood cells from fish, birds, frogs, dogs, and humans Therefore, it was known that cells are found in animals as well as plants Therefore, it was known that cells are found in animals as well as plants

Year Gap??? Between the Hooke/Leuwenhoek discoveries and the mid 19 th century, very little cell advancements were made. Between the Hooke/Leuwenhoek discoveries and the mid 19 th century, very little cell advancements were made. This is probably due to the widely accepted, traditional belief in Spontaneous Generation. This is probably due to the widely accepted, traditional belief in Spontaneous Generation. Examples: Examples: -Mice from dirty clothes/corn husks -Maggots from rotting meat

19 th Century Advancement Much doubt existed around Spontaneous Generation Much doubt existed around Spontaneous Generation Conclusively disproved by Louis Pasteur Conclusively disproved by Louis Pasteur Pasteur: Ummm, I don’t think so!!! + = ?

Development of Cell Theory German Botanist, Matthias Schleiden, concluded that all plant parts are made of cells German Botanist, Matthias Schleiden, concluded that all plant parts are made of cells German physiologist, Theodor Schwann, who was a close friend of Schleiden, stated that all animal tissues are composed of cells German physiologist, Theodor Schwann, who was a close friend of Schleiden, stated that all animal tissues are composed of cells.

Development of Cell Theory Rudolf Virchow, a Prussian physician, concluded that cells must arise from preexisting cells Rudolf Virchow, a Prussian physician, concluded that cells must arise from preexisting cells.

The Cell Theory Complete The 3 Basic Components of the Cell Theory were now complete: The 3 Basic Components of the Cell Theory were now complete: 1. All organisms are composed of one or more cells. (Schleiden & Schwann)( ) 1. All organisms are composed of one or more cells. (Schleiden & Schwann)( ) 2. The cell is the basic unit of life in all living things. (Schleiden & Schwann)( ) 2. The cell is the basic unit of life in all living things. (Schleiden & Schwann)( ) 3. All cells are produced by the division of preexisting cells. (Virchow)(1858) 3. All cells are produced by the division of preexisting cells. (Virchow)(1858)

How Has The Cell Theory Been Used? The basic discovered truths about cells, listed in the Cell Theory, are the basis for things such as: The basic discovered truths about cells, listed in the Cell Theory, are the basis for things such as: Disease/Health/Medical Research and Cures(AIDS, Cancer, Vaccines, Cloning, Stem Cell Research, etc.) Disease/Health/Medical Research and Cures(AIDS, Cancer, Vaccines, Cloning, Stem Cell Research, etc.)

MODERN MICROSCOPES A microscope is simple or compound depending on how many lenses it contains A microscope is simple or compound depending on how many lenses it contains A lens makes an enlarged image & directs light towards you eye A lens makes an enlarged image & directs light towards you eye

COMPOUND MICROSCOPE A compound microscope has multiple lenses A compound microscope has multiple lenses (eyepiece & objective lenses) (eyepiece & objective lenses)

TOTAL MAGNIFICATION Powers of the eyepiece (10X) multiplied by objective lenses determine total magnification.

ELECTRON MICROSCOPES More powerful; some can magnify up to 500,000X More powerful; some can magnify up to 500,000X Use a magnetic field in a vacuum to bend beams of electrons Use a magnetic field in a vacuum to bend beams of electrons at thin slices of cells at thin slices of cells Images must be photographed or produced electronically Images must be photographed or produced electronically

Transmission Electron Microscope (TEM) produces 2D image of thinly sliced specimen produces 2D image of thinly sliced specimen detailed cell parts (only inside a cell) can be observed detailed cell parts (only inside a cell) can be observed

Scanning Electron Microscope (SEM) produces realistic 3D image produces realistic 3D image only the surface of specimen can be observed only the surface of specimen can be observed

Scanning Tunneling Microscope (STM) Able to show 3-D arrangement of atoms Able to show 3-D arrangement of atoms Can be used with live specimens Can be used with live specimens

Prokaryotic Cells Cells without a nucleus of other membrane bound organelles Cells without a nucleus of other membrane bound organelles Unicellular organisms Unicellular organisms (bacteria) (bacteria)

Eukaryotic Cells Contain a nucleus and other organelles that are bound by membranes. Contain a nucleus and other organelles that are bound by membranes. Organelles developed specific functions Organelles developed specific functions Endosymbiont theory Endosymbiont theory

Common traits among cells Plasma membrane Plasma membrane Have genetic material in some form Have genetic material in some form Break down molecules to generate energy for metabolism Break down molecules to generate energy for metabolism

Some Parting Thoughts It is amazing to think that the cells that make up our bodies are just as alive as we are. Humans are just an intricately designed community of cells, which must work together to survive. It is amazing to think that the cells that make up our bodies are just as alive as we are. Humans are just an intricately designed community of cells, which must work together to survive.

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