The Cell Membrane

1. The Cell Membrane Selectively Permeable??

2. CATALYST • Bell Ringer • What is the title of each of these graphs? • How much snow fell in 2003 and how much money was spent on road repairs? • Is there a relationship between the amount of snowfall per year and the amount of money spent on road repairs each year?

3. Objective/Agenda Objective: Agenda: Bell Ringer Announcements Lecture Analysis Questions Homework • SWBAT: Describe how a cells’ plasma membrane functions.

4. Plasma Membrane

5. How is a window screen similar to a plasma membrane? What are some things that can pass through a window screen? What are some things that cannot? Why is it important to keep these things from moving through the screen? The cell is surrounded by a plasma membrane, which regulates what enters and leaves the cell. Why is it important to regulate what moves into and out of a cell?

6. Take Notes! 1. Allow glucose, amino acids, and lipids into and out of the cell 2. Allow waste to leave the cell Ex. Carbon Dioxide The job of the plasma membrane is to:

7. Take Notes! • It allows some molecules in while keeping others out • It keeps the cell in balance with the outside environment How is the membrane selectively permeable? How does the membrane maintain homeostasis?

8. Homeostasis requires the inside of the cell to be similar to the outside. INSIDE CELL Which means… Sometimes things need to move back and forth! OUTSIDE CELL

9. Demo • In what way does this sandwich bag represent a cell? • How was the coffee filter analogous to a cell membrane?

10. Think, Pair, Share • Think: Write down your own analogy for the cell membrane. • Pair: turn to your partner and critique their analogy. • Share: Pick the best analogy at your table to share aloud with the class.

11. Take Notes! • Made up of a lipid bilayer • Transport proteins are tunnels that allow certain substances in and out of the cell Describe the structure of the plasma membrane:

12. Take Notes! The bilayer creates a “sea” where other molecules float along the surface creating patterns or “mosaics”. Fluid Mosaic Model

13. Label Your Diagram! 3. Carbohydrate chains 1. Phospholipid (polar head) 2. Cholesterol 4. Transport Proteins 5. Fatty acid tail (nonpolar tail)

14. Check For Understanding What structure is analogous to a sewage system?

15. Analysis Questions: • 1. Describe why the structure of the plasma membrane is referred to as a fluid mosaic. • 2. What are the specialized parts of the lipid bilayer, and how do their structures relate to the structure of the plasma membrane.