1. Biology: Tissues, Organs, and Systems of Living Things

2. ALL ABOUT CELLS

3. A Short History Lesson
Robert Hooke (1665) first discovered cells - cork
Schwann and Schleiden (1838) first hypothesized that all organisms are composed of cells
First to distinguish between plant and animal cells 3

4. It has been estimated that there are 10 times more cells in the human body than stars in the Milky Way.

5. Cell Theory All living things composed of cells
Cells are basic unit of living organisms
All cells come from existing cells

6. Cell Theory The Human body is estimated to have 100 trillion cells.
Cells are specialized to perform various tasks.
Examples:
Nerve Cells transmit electrochemical messages.
Muscle Cells contract.
All cells:
Digest nutrients
Excrete wastes
Reproduce

7. Prokaryotic vs. Eukaryotic

9. Prokaryotic Cells No internal compartments No organelles
1-celled organisms
Eg. bacteria

10. Prokaryotic Cells Smaller DNA located in nucleoid region
May not need O2

11. Eukaryotic Cells Have internal compartments Have organelles
1-celled or multi- celled organisms
Eg. Plant cell

12. Eukaryotic Cells Larger cells DNA located in the nucleus
Usually need O2

13. Ticket out of Class!
On a scrap piece of paper provided answer the following question:
Are your cells prokaryotic or eukaryotic? Explain.
Hand the paper in, with your name on it
Homework: Textbook Page 32 Questions 1 and 3 13