1. 3.3 Cell Membrane
Sponge: Set up Cornell Notes on pg. 27 Topic: 3.3 Cell Membrane Essential Question: Explain how membrane receptors transmit messages across the cell membrane
2.1 Atoms, Ions, and Molecules
Explain how membrane receptors transmit messages across the cell membrane
Key Concept: The cell membrane is a barrier that separates a cell from the external environment

2. p 27:
Explain why animal cells cannot undergo photosynthesis.
Hint: Look at the difference in organelles.

3. Animals cannot make their own
Animal cells lack chloroplasts which is the organelle needed to convert solar energy into energy that the cell can use.
Animals cannot make their own
food…plants can because they have
chloroplasts!

4. Phospholipid (visual vocab)
pg. 26
Phospholipid (visual vocab)
Cell Membrane (fig 3.17)
“Selectively Permeable” (fig 3.18)

5. Pg
Cell membrane
Phospholipid
head
Tail
Fluid mosaic model
Selective permeability
Receptors

6. What can we compare this to in our bodies?
KEY CONCEPT The cell membrane is a barrier that separates a cell from the external environment.
What can we compare this to in our bodies?

7. The cell membrane has two major functions.

8. The cell membrane has two major functions.
1. forms a boundary between inside and outside of the cell
cell membrane
outside cell
inside cell

9. The cell membrane has two major functions.
1. forms a boundary between inside and outside of the cell
2. controls passage of materials
cell membrane
outside cell
inside cell

10. Cell membranes are composed of two phospholipid layers.

11. A phospholipid is a molecule composed of three basic parts:
A charged phosphate group
Glycerol
two fatty acid chains
head
tail
*Draw and label this phospholipid on the top of pg 26

12. Attracted to other tails
Head
The head is polar
interacts with water
Hydrophilic
Attracted to water
The tail is non-polar
repelled by water
hydrophobic
Attracted to other tails
Tail

13. *Phospholipids arrange themselves like a sandwich into two layers.
Contain:
Proteins
Cholesterol
Carbohydrates
protein
cholesterol
carbohydrate
chain
protein channel
cell membrane

14. Pg. 26-middle: draw and label the cell membrane and its parts
protein
cholesterol
carbohydrate
chain
protein channel

15. Fluid mosaic model:
Flexible
Phospholipids can move from side to side and slide past one another
Behaves like a fluid

16. If the cell membrane was rigid (solid or hard), as opposed to fluid (oil or liquid like), explain why the membrane would no longer be selectively permeable.

17. The phospholipids would be unable to move to allow material in or out!
If the membrane was rigid:
The phospholipids would not be able to move from side to side or slide past one another
The phospholipids would be unable to move to allow material in or out!

18. The cell membrane is selectively permeable.
*Draw a picture on the bottom of pg. 26
Some molecules can cross the membrane while others cannot.

19. The cell membrane is selectively permeable.
*Draw a picture on the bottom of pg. 26
Some molecules can cross the membrane while others cannot.

20. Receptors are proteins that detect a signal molecule and performs an action in response
It binds with ligands on the outside of the cell
Once they bind, the receptor changes shape and sends a message to the inside of the cell

21. In Da Club- Membranes and Transport (6m37s)
Intro to Passive (diffusion/osmosis) and active transport