1. Ch. 2-3: Discovering Cells
Discover Activity: Seeing is believing??
What is one thing you could see with the hand lens that you could not see with only your eyes?
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2. What additional could you see only with the microscope?

2. Cells Cells and Structures Cells and Function Many and Few
The basic units of structure and function in living things.
Structures of living things are determined by the variety of ways in which cells are put together.
Organism’s functions are the processes that enable it to stay alive and reproduce.
One square centimeter on your skin contains more than 100,000 cells.
Cells
Cells and Structures
Cells and Function
Many and Few

3. First Observations of Cells
The invention of the microscope: made is possible for people to discover and learn about cells.
1590
Contains only one lens
Simple Microscope
Contains more than one lens
Compound Microscope

4. First Observations of Cells Continued
Observed thin slices of cork. The empty spaces in the cork looked like tiny rooms: cells.
Robert Hooke
Discovered one-celled moving organisms from lake water, teeth/gum scrapings, etc.
Anton van Leeuwenhoek
What type of microscope did Leeuwenhoek use?
What type of microscope did Leeuwenhoek use?

5. Development of the Cell Theory
German scientists who helped developed the cell theory
Schleiden, Schwann, and Virchow
All living things are composed of cells.
Cells are the basic units of structure and function in living things.
All cells are produced from other cells. 1.
Cell Theory 2. 3.

6. Light and Electron Microscopes
Lenses in microscopes magnify an object by bending the light
Illustration
Magnification and Lenses
Total magnification of microscope = magnifications of two lenses multiplied together
Compound Microscope Magnification
Example
Resolution
Ability to clearly distinguish the individual parts of an object
Electron Microscopes
Electron microscopes use a beam of electrons instead of light to produce a magnified image

7. Lab Zone: Skills Activity
Follow procedures 1-5 from Lab Zone Skills Activity p. 55.
Draw what you see: Draw what you see:
Lab Questions:
How does your drawing in step 3 compare to Hooke’s description of cells on page 52?
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Based on your observations in Step 5, why did Leeuwenhoek call the organisms he saw “little animals”?

8. Section 3 Assessment
Directions: Use your notes and the book to answer the following questions on a separate sheet of paper
A. Define Structure and Function.
B. Explain this statement: Cells are the basic units of structure and function in organisms.
C. In what important function are the cells in your eyes involved?
A. What does a microscope enable people to do?
B. Summarize Hooke’s observations of cork under a microscope.
C. Why would Hooke’s discovery have been impossible without a microscope?
A. What are the main ideas of the cell theory?
B. What did Virchow contribute to the cell theory?
C. Use the ideas of Virchow to explain why plastic plants and stuffed animals are not alive.