1. Cells & Their Environment Unit 7

3. Some Random Cell Facts
The average human being is composed of around 100 Trillion individual cells!!!
It would take as many as 50 cells to cover the area of a dot on the letter “i”

4. Microscopes
In the 1600’s Anton van Leeuwenhoek described red blood cells & bacteria from his teeth
1673- Used a handmade microscope to observe pond scum & discovered single-celled organisms
Used a simple microscope

5. Simple Microscope
Little more than a magnifying glass, still with Leeuwenhoek’s skill as a lens grinder he achieved 200x magnification.

6. Robert Hooke
In 1665 Robert Hooke, English scientist, used a compound light microscope to examine cork cells
Saw tiny hollow boxes, named the cells after the living quarters of monks
He thought that cells only existed in plants and fungi

7. Year Gap???
Between the Hooke/Leuwenhoek discoveries and the mid 19th century, very little cell advancements were made.
This is probably due to the widely accepted, traditional belief in Spontaneous Generation.
Examples:
-Mice from dirty clothes/corn husks
-Maggots from rotting meat

8. 19th Century Advancement
Much doubt existed around Spontaneous Generation
Conclusively disproved by Louis Pasteur ? + =

9. Schleiden & Schwann
Schleiden looked at plants & concluded that all plants are made of cells.
Schwann looked at animals & said all animals were made of cells

10. Virchow
All cells come from pre-existing cells

11. These observations led to the Cell Theory

12. 1. All organisms are composed of one or more cells. (S & S)
Part 1 of the Cell Theory:
1. All organisms are composed of one or more cells. (S & S)

13. Part 2 of the Cell Theory:
2. The cell is the basic unit of function and organization of all organisms. (S & S)

14. 3. All cells are produced by the division of pre-existing cells. (V)
Part 3 of the Cell Theory:
3. All cells are produced by the division of pre-existing cells. (V)

15. Modern Cell Theory
Modern Cell Theory contains 4 statements, in addition to the original Cell Theory:
1. The cell contains hereditary information(DNA) which is passed on from cell to cell during cell division.
2. All cells are basically the same in chemical composition and metabolic activities.
3. All basic chemical & physiological functions are carried out inside the cells (movement, digestion,etc).
4. Cell activity depends on the activities of sub- cellular structures within the cell (organelles, nucleus, plasma membrane).

16. How Has The Cell Theory Been Used?
The basic discovered truths about cells, listed in the Cell Theory, are the basis for things such as:
Disease/Health/Medical Research and Cures(AIDS, Cancer, Vaccines, Cloning, Stem Cell Research, etc.)

17. Some Parting Thoughts
It is amazing to think that the cells that make up our bodies are just as alive as we are. Humans are just an intricately designed community of cells, which must work together to survive.

18. Compound microscopes
Microscope that uses a image observed through two lenses.
Used to look at cells & small organisms, magnifies up to 1500X
The magnification is determined by multiplying the two lenses power together.
10 x 40 = 400

19. Electron Microscopes
An item is placed in a vacuum and a stream of electrons are aimed at the item. The image is transferred to a computer screen.

20. TYPE OF ELECTRON MICROSCOPES
TEM- Transmission Electron Microscope, used to study detailed parts of the cell, magnify hundreds of thousands of times
SEM- Scanning Electron Microscope, D images, but can only see the surface, magnify 60,000X
STM- Scanning Tunneling Microscope, show arrangement of atoms on the surface of a molecule

21. TEM
Bacteria cells
SEM
Sperm cells
STM
Surface of Platinum

22. Prokaryote
Usually a unicellular organism that lacks internal organelles surrounded by membranes.
Has a cell membrane & DNA but NO NUCLEUS!
Ex: bacteria

23. Eukaryote HAS A NUCLEUS!
More complex cell, unicellular or multicellular organisms. Has membrane- bound internal organelles.
HAS A NUCLEUS!
Ex: plants, animals, fungi, protists

24. Tissue: A group of cells that function together to perform an activity

25. Organ: Group of 2 or more tissues that function together. (stomach)

26. Organ System: A group of organs that make a life function efficient
Organ System: A group of organs that make a life function efficient. (organism)

27. SO…
Cells form Tissues
Tissues form Organs
Organs form Systems

28. Plant & animal cells are EUKARYOTES!
Remember:
All eukaryotes have a nucleus!

29. 3 Differences between plant & animal cells:
1. Plant cells have a cell wall.
2. Plant cells have chloroplasts.
3. Plant cells have 1 large central vacuole and animal cells have many small vacuoles.

30. Animal Cell vs. Plant Cell

31. Why are cells so small? GEOMETRY!!
Average cell is 50 micrometers in diameter.
As any shape gets larger the interior increases at a faster rate than the surface area (ratio gets smaller as the cell gets larger).

32. Cells rely on the surface to allow materials to enter and exit the cell and support the organelles.
Too large a cell results in too little surface area to support the interior.