Unit 2: Cells Cell Theory 1

•Theories are explanations of natural phenomena

•Why something happens

•Explanation of nature

•Based on evidence

•Example: Germ Theory (how diseases are caused)

THEORY

•Laws are verified statements/descriptions of natural phenomenon

•Describes what will happen

•Predicts outcomes

•Based on evidence

•Example: Newton’s Law of Gravity

LAW

The Cell Theory

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

CURRENT CELL THEORY

Before the Cell Theory people believed in spontaneous generation which means living things came from non-living things.

Two scientists disproved spontaneous generation: Francisco Redi and Louis Pasteur

BEFORE

All known living things are made up of cells.

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

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