1. Baltimore Polytechnic Institute
Ingenuity Honor’s Biology
November 26th, Monday
Unit 3: Cells; cell theory, microscopes
Insong James Lee, Ph.D.

2. Unit 3: cells; cell theory, microscopes
November 26th, Monday
Learning objectives:
• Provide a brief history of microscopes and their use.
Name and explain the three components of the cell theory.
Discuss the relative size of cells.
Explain the theory of spontaneous generation and how it was disproven.
Unit 3: cells; cell theory, microscopes

3. cells, cell theory, microscopes
Topic slides
Brief history of the microscope. 4-8
Cell theory, parts I and II
Spontaneous generation and
cell theory, part III.

4. Microscope
slides 5-8

5. Hooke’s microscope
Microscopes were first invented and used a little over 300 years ago. (late 1600s)
Robert Hooke and Anton Van Leeuwenhoek were the first scientists to study cells with microscopes like this one.

6. In the 1660’s, Robert Hooke looked through a primitive microscope at a thinly cut piece of cork. He saw a series of walled boxes that reminded him of the tiny rooms, or cellula, occupied by monks.

7. They were the first people to see a whole new world of tiny organisms
They were the first people to see a whole new world of tiny organisms. Recognize this one?

8. Microscopes have come a long way since then!
Advances in technology often cause advances in science. Today’s scientists can see all sorts of things…

9. Cell theory I and II
slides 10-17

10. Cells are the smallest units of life
CELL THEORY PART 1: Every organism is made of one or more cells.
Cells are very small, and require a microscope to be seen individually.
CELL THEORY PART 2: Cells are the smallest unit of life

11. The average human body contains approximately 37.2 trillion cells!
The cells shown below are neurons. There are billions of neurons in your brain.

12. Systems of specialized cells work together in tissues and organs – like the eye, for example

13. Your body is made of cells, from your liver (left) to your muscles (bottom)
Why do you think
they look so different?

14. There’s practically no limit to the number of different types of cells in nature!

15. All of these microscopic organisms are made of cells too!

16. Cells interact with each other just like organisms do – what’s going on here?

17. It’s a life or death struggle – can you guess what this is a picture of?

18. Cell theory III
slides 19-27

19. Will this “recipe” for creating mice work? Why or why not?

20. Spontaneous Generation?

21. History of theory of spontaneous generation
Spontaneous Generation: the false belief that living things arise from non-living material today.
Was widely believed to be true until the 17th century

23. Pasteur Verbal Smackdown of S.G.
"Never will the doctrine of spontaneous generation recover from the mortal blow struck by this experiment." - Louis Pasteur
The “swan neck flask” experiment is famous.
CELL THEORY PART 3: “Cells come only from preexisting cells.”

24. So Where did the first cells come from?
Probably only possible in a lifeless world.
Self-replicating RNA molecules enclosed within lipid bubbles is the leading idea
Chemicals of life are easily produced by inorganic processes.

25. What is the size of a cell
What is the size of a cell? About 1,000 times BIGGER than molecules About1,000 times smaller than you can see with the naked eye

26. There are two basic types of cells
There are two basic types of cells. Eukaryotic cells are larger, more complex, and have a nucleus. Humans, as well as all other animals and plants are made of eukaryotic cells Prokaryotic cells, like bacteria, are all unicellular, small, and simple. They have no nucleus or mitochondria

27. Remember that cell theory!
All living things have 1 or more cells.
2. Cells are the basic units of structure & function in organisms.
3. Cells come only from preexisting cells.