1. Introduction to the Cell

2. The Cell Cell: the smallest unit of life
Why do you think they weren’t discovered until the mid 1600’s?

3. Used an early compound light microscope
The Cell
Robert Hooke-first person to describe a cell
1665 British-
Used an early compound light microscope

4. Looked at cork "little boxes”; reminded him of monastery rooms called
The Cell
Looked at cork "little
boxes”; reminded
him of monastery
rooms called
cells

5. Dutch; around the same time as Hooke; used a single- lens microscope
The Cell
Anton van Leeuwenhoek
Dutch; around the same time as Hooke; used a single- lens microscope

6. Anton van Leeuwenhoek-
The Cell
Anton van Leeuwenhoek-
made his own microscopes and looked at protists, animal blood, bacteria, and yeast

7. 1838 botanist Schleiden 1839 biologist Schwann 1855 physician Virchow
The Cell
The Cell Theory:
1838 botanist Schleiden
1839 biologist Schwann
1855 physician Virchow

8. 1. All organisms are made up of cells
The Cell
The Cell theory:
1. All organisms are made up of cells

9. 1. All organisms are made up of cells
The Cell
The Cell theory:
1. All organisms are made up of cells
2. The cell is the basic unit of life

10. 3. All cells come from existing cells
The Cell
The Cell theory:
1. All organisms are made up of cells
2. The cell is the basic unit of life
3. All cells come from existing cells

11. Parts of All Cells
All cells are surrounded by a protective barrier called the cell membrane.

12. Parts of All Cells
All cells have structures that perform specific functions within the cell called
organelles

13. Parts of All Cells
All cells contain DNA (some cells have a nucleus that holds the DNA)

14. Two Kinds of Cells:
1. Prokaryotes (single celled with no nucleus or membrane bound organelles)
Example 1:
Bacteria
Smallest of all cells
Common
Strong cell wall

15. Two Kinds of Cells: Prokaryotes Example 2: Archaea
Heat-loving,
salt-loving, and methane-making
Live in extreme conditions
Thought to have evolved prior to nuclei developing

16. Two Kinds of Cells:
2. Eukaryotes (the largest cells; more complex; have a nucleus and other membrane bound organelles)

17. Two Kinds of Cells: Eukaryotes Many are multi-cellular (many cells)
Great variety!
Examples:
Plants, animals, fungi, protists

18. Surface Area to Volume Ratio
Why are most cells so small?
As the cell’s volume increases, so does its surface area.

19. Surface Area to Volume Ratio
Volume grows faster than surface area (inside grows faster than membrane)

20. Surface Area to Volume Ratio
If gets too large- cell’s s.a. will not be large enough to take in enough nutrients or pump out wastes

21. Eventually there is just enough surface available to service all the interior; if it is to survive, the cell must stop growing!
The cell must ÷ into smaller cells with smaller s.a. /volume ratios, or cease to function.

22. Surface Area to Volume Ratio
Remember:
The surface area to the volume ratio gets smaller as the cell gets larger.