Chapter 3
Cell Structure & Function
Learning Targets
• What is the difference between a scientific theory and law?
• Understand and apply the cell theory.
Theory vs “theory” vs Law
• A scientific law is a description of observed
patterns in Nature
• A scientific law is based off of hypotheses (NOT
theories)…many of them…
• EX: Newton’s Laws of Motion
Theory vs “theory” vs Law
• “Theory” in every day language is NOT the same
thing as a theory in science!!!
• “Theories” in everyday language is usually a
guess….
• Ex: “I have a theory that ice cream makes you
smarter”
Theory vs “theory” vs Law
• A scientific theory is a well-substantiated
explanation of some aspect of the natural world that
is acquired through the scientific method and
repeatedly tested
•NOT
just some “idea” or guess
• EX: Cell Theory
Cell Theory:
History
• Robert Hooke
• English--1665
• 1st to view/name “cells”
• Anton van Leeuwenhoek
• Dutch lens grinder--1666
• 1st to see “animalcules”
Cell Theory:
History
• Schleiden
• 1838
• Plants are made of cells
• Schwann
• 1839
• Animals are made of cells
• Virchow
• 1855
• Cells come only from other cells
Cell Theory
1. All living things (plants, animals, bacteria) are made
up of cells
2. Cells are the basic structural and functional unit of
life
1. Cells only come from pre-existing cells
Learning Check
• Compare and contrast theories, scientific theories and laws?
• Make a table/chart with the similarities and differences
• What is the cell theory?
• What are the 3 parts to the cell theory
Extra Resources
• Law vs Theory
• http://www.livescience.com/21457-what-is-a-law-in-science-definition-ofscientific-law.html
• Cell Theory History
• https://www.youtube.com/watch?v=4OpBylwH9DU