Cell Membrane: Transmitting Messages and Selective Permeability

1. 3.3 Cell Membrane 2.1 Atoms, Ions, and Molecules 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 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. 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 Cell Membrane (fig 3.17) “Selectively Permeable” (fig 3.18)

5. Pg. 81-84 • Cell membrane • Phospholipid • head • Tail • Fluid mosaic model • Selective permeability • Receptors

6. 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. cell membrane • The cell membrane has two major functions.

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

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

10. Cell membranes are composed of two phospholipid layers.

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

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

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. 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) https://www.youtube.com/watch?v=dPKvHrD1eS4 Intro to Passive (diffusion/osmosis) and active transport