1. Cell Membrane Structure

2. BUBBLES!! MUST wear goggles at ALL times!
NO taking straw out of the dish!
NO drinking/ inhaling bubble fluid
THIS IS an EXPERIMENT!!!
You can have fun, but ALL usual lab safety RULES APPLY!

3. Questions to think about:
Can anything pass through the bubble without breaking it?
Can one bubble divide to become several bubbles?
Can several bubbles merge to form one- how?
Can a drop of water pass through a bubble without popping it?
Does it look like the surface of the bubble moves? How can you tell?

4. Bubble Summary! A bubble is a lipid monolayer!!
How does a bubble model the fluid nature of a cell membrane?
What is the structure of the membranes of our cells?

5. AS Biology. Foundation. Cell membranes and Transport
Key words to know!
Hydrophilic
Hydrophobic
Cell Membrane
Fluid Mosaic Model
Phospholipid
Cholesterol
Diffusion
Osmosis
Selectively Permeable
Passive Transport
Active Transport
AS Biology. Foundation. Cell membranes and Transport

6. Learning Objectives
Describe the fluid mosaic model of membrane structure and explain the reasons for its structure.
Outline the roles of phospholipids, cholesterol, glycolipids, proteins and glycoproteins in membranes.
Outline the roles of the plasma membrane, and the roles of membranes within cells.

7. Cell Membranes AKA Plasma membrane
What are the functions of the cell membrane?
How does its structure allow it to carry out its functions?

8. Cell (plasma) Membrane
Encloses the cell’s contents
Selectively Permiable- regulates which particles (nutrients, wastes) can enter and exit the cell.
Cell communication recognition
AS Biology. Foundation. Cell membranes and Transport

9. Cell Membranes:
Every cell is enclosed by a double layer of phospholipids.

10. Cell Membrane Structure
Building blocks are phospholipids…
Lipid with a phosphate group in place of one fatty acid chain.
Phosphate head is hydrophilic, fatty acid tail is hydrophobic.
AS Biology. Foundation. Cell membranes and Transport

12. Phospholipids have Split Personalities!
HYDROPHOBIC tails (the fatty acid portion)- HATE water!!
HYDROPHILIC heads (phosphate group)- LOVE water!!
AS Biology. Foundation. Cell membranes and Transport

13. Phospholipid Bilayer

14. Properties of Cell Membranes
Phospholipids act as a barrier to most water soluble substances... (“water and oil don’t mix”)
AS Biology. Foundation. Cell membranes and Transport

15. What is a mosaic?

16. AS Biology. Foundation. Cell membranes and Transport
Fluid Mosaic Model
Phosopholipids, cholesterol and proteins form a mosaic (pattern) within the cell membrane
AS Biology. Foundation. Cell membranes and Transport

18. Why call it a Fluid Mosaic Model?
FLUID- phospholipids and some proteins move around freely within the layer
MOSAIC- the pattern produced by scattered protein molecules in the membrane.
AS Biology. Foundation. Cell membranes and Transport

19. Visualizing structure and function
AS Biology. Foundation. Cell membranes and Transport

20. Functions of Proteins in Cell Membrane
Proteins act as channels for substances to move in or out of cell.
Some act as membrane enzymes in chemical reactions.
Glycoproteins act as receptors for cell communication and recognition.
AS Biology. Foundation. Cell membranes and Transport

21. Function of Cholesterol In Cell Membrane
Cholesterol (a lipid) is found between the phospholipid molecules in the cell membrane.
Help maintain stability of the membrane…not too fluid, not too rigid.

22. Functions of components of cell membranes
Component Description Function
1. Phospholipids
2. Proteins
3. Cholesterol
AS Biology. Foundation. Cell membranes and Transport