1. Selectively Permeable??
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:
SWBAT: Describe how a cells’ plasma membrane functions.
Bell Ringer
Announcements
Lecture
Analysis Questions
Homework

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

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

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

9. In what way does this sandwich bag represent a cell?
Demo
In what way does this sandwich bag represent a cell?
How was the coffee filter analogous to a cell membrane?
I am filling a bag with marbles to represent the inside of the cell and putting it in water. The second one is to filter water through coffee.

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

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

13. Label Your Diagram! 3. Carbohydrate chains
1. Phospholipid (polar head)
2. Cholesterol
Make sure to explain the analogy between the transport proteins and a sewer system. (This is on the exam) Remember to speak about the importance of the polar and nonpolar structures of the cell membrane here also.
4. Transport Proteins
5. Fatty acid tail (nonpolar tail)

14. Check For Understanding
What structure is analogous to a sewage system?
Test question! You may also want to point out where the student would least likely find water (E). That is also a test question. a. A c. C b. B d. D

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.