1. Basic Structure of a Cell

2. History of Cells & the Cell Theory
Cell Specialization
Virchow

3. First to View Cells
In 1665, Robert Hooke used a microscope to examine a thin slice of cork (dead plant cells)
What he saw looked like small boxes

4. First to View Cells Hooke is responsible for naming cells
Hooke called them “CELLS” because they looked like the small rooms that monks lived in called Cells

5. Anton van Leeuwenhoek
In 1673, Leeuwenhoek (a Dutch microscope maker), was first to view organisms (living things)
Leeuwenhoek used a simple, handheld microscope to view pond water & scrapings from his teeth

6. Robert Brown Discovered & named the nucleus
The dark area in the center of the cell

7. Beginning of the Cell Theory
In 1838, a German botanist named Matthias Schleiden concluded that all plants were made of cells
Schleiden is a cofounder of the cell theory

8. Beginning of the Cell Theory
In 1839, a German zoologist named Theodore Schwann concluded that all animals were made of cells
Schwann also cofounded the cell theory

9. Beginning of the Cell Theory
In 1855, a German medical doctor named Rudolph Virchow observed, under the microscope, cells dividing
He reasoned that all cells come from other pre-existing cells by cell division

10. CELL THEORY All living things are made of cells
Cells are the basic unit of structure and function in an organism (basic unit of life)
Cells come from the reproduction of existing cells (cell division)

11. Cell Size: Surface Area & Volume
As cells get larger, their volume increases at a faster rate than their surface area
Why is this a problem?
Cells depend on their surfaced area to move needed materials into the cell and waste materials out of the cell
If the surface area decreases, cell cannot move materials fast enough
Therefore, cells must be small to maintain a high surface area to volume ratio

12. Prokaryotic Cells Basic Description: has NO membrane-bound organelles
Nucleus? Has NO nucleus
Ribosomes? Present
Arrangement of Chromosomes? Single chromosome, free-floating in the cytoplasm
May contain plasmids
Examples: Bacteria (Bacterium – singular)
Sketch a Prokaryotic
cell and label it.

13. Eukaryotic Cells Basic Description? Has membrane-bound organelles
Nucleus? Has a true nucleus
Ribosomes? Present – protein factory
Arrangement of Chromosomes? Many linear strands of DNA
Examples? Plants, animals, fungi, & protists (everything except for bacteria)
Sketch and label a basic eukaryotic cell and

14. Plant Cell

15. Animal Cell

16. Plant vs. Animal Cells QUESTION? PLANT CELL ANIMAL CELL
Cell wall and/or cell membrane?
Cell Wall AND Cell Membrane
Cell Membrane only
Chloroplast or no chloroplast?
Chloroplast
(for photosynthesis)
No chloroplast
Vacuole or not vacuole?
Vacuole (often large to store water)
Small vacuole

17. Cell Organization
Cells 
Tissues 
Organs 
Organ Systems 
Organism

18. Typical cells range from 5 – 50 micrometers (microns) in diameter
CELL SIZE
Typical cells range from 5 – 50 micrometers (microns) in diameter

19. How Big is a Micron ( µ ) ?
1 cm = 10,000 microns 1” = 25,000 microns

20. Which Cell Type is Larger?
_________ > _____________ > ___________
Plant cell
Animal cell
Bacteria or
Prokaryotes

21. Specialized Animal Cells
Muscle cells
Red blood cells
Cheek cells
Neuron

22. Specialized Plant cells
Guard Cells
Pollen
Xylem cells

23. What causes a cell to become specialized?
Differentiation
Occurs in stem cells
Specific parts of DNA (called genes) are turned on
Once activated or turned on, specific types of cells are made
This is why all cells in an organism have the exact same DNA, but each stem cell may differentiate or become any type of specialized cell.

24. Communication Among Cells
Types of Chemical Signals
A) Hormones  chemical signals made by an endocrine gland and released in to the body

25. Communication Among Cells
Neurotransmitters  chemical signals released by nerve cells
Used to communicate with other nerve cells or muscle cells

26. Receptor Proteins
Proteins of the surface of a cell that “receive” chemical signals
A ) Receptor proteins can influence the cell in 3 ways
**Receptor chemically changes molecules in the
cell’s cytoplasm
**Receptor causes a 2nd signal to form inside the
cell
**Receptor can open a passageway into the cell.