1. Cell Membrane Structure and Function
Activity 9
Cell Membrane
Structure and Function

3. The Cell Membrane
Ask students to state what they learned about the basic characteristics of the cell membrane in the bubble model from Activity 7, “A Model Membrane.” Possible student responses are described in your Teacher’s Edition for this activity.

4. Read the introduction.
What basic characteristics of the cell membrane have you learned from models in the previous activities?
Students have modeled that the membrane is fluid and flexible. They have also modeled transport channels.

5. How do the structures of the cell membrane help it function?
Challenge
How do the structures of the cell membrane help it function?

6. The questions in the reading do not require a written response, but you should answer them in your mind. The answers will help you to understand the reading.
For more information on using this literacy strategy with your students see your Teacher’s Edition for this Activity and see Teacher Resources III: Literacy.
Sample responses for Stopping to Think sections 1-3 are in the Teacher’s Edition for this activity.

7. Analysis 3 A. What are the functions of the cell membrane?
B. Explain which parts of the cell membrane allow it to perform these functions.
Analysis Question 3 may be scored using the Understanding Concepts (UC) scoring variable. More information and a sample student response can be found in your Teacher’s Edition for this activity.

8. Analysis 5
Explain how the cell membrane helps the cell maintain homeostasis – a stable internal environment. Name specific structures of the cell membrane and describe their functions in your explanation.
Analysis Question 5 may be scored using the Understanding Concepts (UC) scoring variable. More information and a sample student response can be found in your Teacher’s Edition for this activity.

9. Analysis 6
Imagine a single-celled organism living in a pond. What would happen to the organism if runoff from irrigation caused the pond to become significantly salty? Use evidence to support your explanation.
Analysis Question 6 may be scored using the Understanding Concepts (UC) scoring variable. More information and a sample student response can be found in your Teacher’s Edition for this activity.

10. How do the structures of the cell membrane help it function?
Revisit the Challenge
How do the structures of the cell membrane help it function?
Discuss the roles of both phospholipids and proteins in membrane function. For more information see your Teacher’s Edition of this activity.

11. cell membrane, membrane passive transport phospholipid diffusion
Key Vocabulary
active transport
osmosis
cell membrane, membrane
passive transport
phospholipid
diffusion
phospholipid (lipid) bilayer
endocytosis
exocytosis
protein
facilitated diffusion
semi-permeable, selectively permeable
fluid mosaic model
lipid
vesicle
lipid bilayer
virus
macromolecule
See Teacher Resources III: Literacy for more information on key vocabulary and the most effective strategies to enhance student vocabulary learning.
Note that bold words are formally defined in this activity. Words in regular font are used in the activity, but not formally defined. The definition of a key vocabulary word should not be discussed as a class prior to the formal definition being introduced.