Cell Theory

Megan StanleyBIO 122

“If I have seen further, it is only by standing on the shoulders of giants”

• Isaac Newton• Science builds

over time

What is a cell?

Types of Cells

Bacteria

Blood Cell Nerve Cell

Skin Cell Cancer Cell

Stem Cell

Is a theory a guess?

No, a scientific guess is a hypothesis. A theory is fact.

Cell Theory

•All living things are made up of one or more cells

•The cell is the basic unit of structure and function

•All cells arise from pre-existing cells

Who came up with the Cell Theory?

• Many different scientists over many years

Why do we care?

• To understand how tissues work• How organs function• Cure disease, such as cancer• Cloning

The Scientific “Giants”

Robert Hooke (1655)

• Coined the term “cell”

Anton van Leeuwenhoek (1674)

• First compound light microscope

Matthias Schlieden (1838)

All plants are made of cells

Theodor Schwann (1839)

All animals are made of cells

Rudolf Virchow (1839)

Cells can only arise from pre-existing cells

Bacteria Viruses

Cause disease Cause disease

Have DNA Have DNA

Replicate Replicate

Evolve Evolve

Living Nonliving

Made up of a cell

Not made up of a cell

Bacterium Virus

Why is bacteria considered living, but a virus considered nonliving?

• A virus is not made up of a cell