1. Cell Structure Introduction to Cells

2. Objectives of this Chapter  Describe relationships between structure and function at the cellular and sub-cellular levels of an organism  Express the common features of cells and the major differences between prokaryotes and eukaryotes  Outline how proper functioning of all cell structures is needed to maintain homeostasis

3. Cell Example - Paramecium  Found in ponds and streams  Classic example of a a eukaryotic cell  Nucleus (actually has more than one)  Moves by cilia  Contractile vacuoles squeeze excess water out of cell

4. What are these cells? Use their structure to predict their function

5. What are these cells? Again – use their structure to predict their function…

6. More cells Structure = Function

7. Cell Features - Objectives  List the 3 parts of the cell theory  Determine why cells must be relatively small  Compare the structure of prokaryotic cells with the structure of eukaryotic cells  Describe the structure of cell membranes

8. Cell Theory -1800s - Schleiden, Schwann and Virchow  All living things are made of one or more cells.  Cells are the basic units of structure and function in living organisms.  All cells arise from existing cells

9. Why are cells so small?

10. Small cells function more efficiently than large cells  Most cells range in size from 5 micrometers to 20 micrometers in diameter.  100 trillion cells in the human body  All substances must enter and leave cell through the membrane  Small cells can transport material more easily because of surface area to volume ratio

11. Surface Area to Volume Ratio