1. Life Science Chapter 2 Section 3 pp. 50- 57
Discovering Cells
Life Science
Chapter 2 Section 3 pp

2. An Overview of Cells What are Cells?
Cells are the basic units of structure and function in living things
Structure-what living things are made of
Function-the processes that keep an organism alive (what
it does (its job)
One square cm of skin contains over
100,000 cells
Skin Cells

3. First Observation of Cells
a MICROSCOPE
is an instrument that makes small things look big
The invention of the microscope made it possible for …
people to discover
and learn about cells

4. First Observation of Cells
A SIMPLE microscope has only one lens
A COMPOUND microscope
has more than one lens

5. Robert Hooke
In 1633, he was one of the first to observe cells with a microscope he made
1633
Hooke used his microscope to look at the structure of a thin slice of cork (the bark of the cork oak tree)
He felt the small empty spaces looked like tiny rectangular rooms, so he called the empty spaces “cells” which is a word meaning “small rooms.”

6. Cork Cells as Drawn by Hooke

7. Cork Cells under 100x Magnification

8. Anton van Leeuwenhoek
(pronounced 'vahn Laywenhook')
a Dutch tradesman and scientist from the Netherlands.
He is commonly known as "the Father of Microbiology".
Using his handcrafted microscopes he was the first to observe and describe single celled organisms

9. Anton van Leeuwenhoek Uses the microscope he built to look at:
Drops of lake water
Scrapings from teeth and gums
Water from rain gutters

10. Animalcules “Little Animals”
Anton van Leeuwenhoek saw moving little animals he called:
Animalcules

11. Microscope Improvements
1590
one of the first compound microscope- uses two lenses

12. Microscope Improvements
1660
Hooke’s compound microscope uses light to help see

13. Microscope Improvements
1674
Leeuwenhoek’s simple microscope can magnify 266 times

14. 1886 Microscope Improvements
Modern Compound Light Microscope can magnify up to 1,000 times

15. Microscope Improvements
1933
Transmission Electron Microscope (TEM)
using electrons, it can magnify up to 500,000 times

16. Microscope Improvements
1965
Scanning Electron Microscope can see in 3D and magnify up to 150,000 times

17. Microscope Improvements
1981
Scanning Tunneling Microscope can magnify up to 1,000,000 times

18. Schleiden, Schwann, and Virchow
1838 Schleiden concludes: ALL plants are made of cells
1839 Schwann concludes:
ALL animals are made of cells
Therefore, ALL LIVING THINGS ARE MADE OF CELLS
However, no one can explain where cells come from
1855 Virchow writes:
New cells are only formed from cells that already exist…
or ALL CELLS COME FROM OTHER CELLS .

19. What the Cell Theory Says
Schleiden, Schwann, Virchow and others helped develop the cell theory. Cell Theory is a widely accepted explanation for the relationship between cells and living things.
THE CELL THEORY STATES THE FOLLOWING:
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.

20. Light and Electron Microscopes
The lenses in light microscopes magnify an object by
bending the light that passes through them

21. Compound Microscope Magnification
Total magnification is equal to the two lenses multiplied together
20x
30x
So 20 x 30 =
600 times larger

22. Electron Microscope
A microscope that uses a beam of electrons instead of light to produce a magnified image is called an ELECTRON microscope
ELECTRON

23. Hidden Worlds… Fly Foot
An image of a streptococcus bacteria taken by a scanning electron microscope. Magnified around 2,000,000x
Fly Foot

24. Electric guitar string
Alien Life???
Weevil
pyralidae moth
Electric guitar string

25. You Know These!!! Edge of a dime leaf Strand of hair Sponge (only 23x)
Snowflake