1. Fluid Mosaic Model a.k.a: Phospholopid Bilayer

2. Cellular membrane Overall functions
- Boundary between intracellular compartments, living cells, and abiotic environment
Selectively permeable –
Some molecules cross membranes more easily than others.

3. Membrane Structure
Mostly made of phospholipids (review your notes on these)
Dual natured molecules: hydrophobic AND hydrophilic
Also has proteins throughout the membrane (see picture)
Membrane organization and properties referred to as a:
FLUID MOSAIC MODEL

4. This bilayer has MANY components…
This bilayer has MANY components….make sure you look at this and study the parts

5. Refer to previous illustration and plate 36 worksheet (test material)
Some proteins are only on the surface of the membrane
Attached to some of the surface proteins are carbohydrate groups that function as identification tags so cells recognize each other and do not attack each other. Find these on plate 36.

6. Organization of membrane phospholipids
LE 7-2
Organization of membrane phospholipids
WATER
Hydrophilic
head
Hydrophobic
tail
WATER

7. Fluid Mosaic Model
Called the F.M.M. because it is hypothesized that the membranes of a cell consist of phospholipid bilayers in which proteins and carbohydrates are also present
The term “mosaic” means made of small parts
Fluid because it is like a fluid so proteins are able to migrate throughout it

8. Mosaic: Proteins dispersed among phospholipids in membrane:
LE 7-3
Mosaic: Proteins dispersed among phospholipids in membrane:
Hydrophilic region
of protein
Phospholipid
bilayer
Hydrophobic region of protein

9. Cholesterol within the animal cell membrane
LE 7-5c
Cholesterol
Cholesterol within the animal cell membrane

10. Movement of membrane proteins
Proteins and lipids Can drift within the bilayer
Picture the ball bin at ChuckE Cheese.
You = proteins/lipids that move through the balls
The balls = phospholipid bilayer
Proteins much larger than lipids so proteins move more slowly

11. Membrane Transport Proteins and their Functions
Some proteins have pores in them that allow facilitated diffusion of small polar molecules
This means small polar molecules can fit through the pores (like tunnels) and get to the other side of the membrane
Facilitate = to help
Diffusion = net movement across the membrane
Polar molecules are able to pass through the pores because the protein pores are also hydrophilic (polar) and allow them to pass

12. Diffusion (3 types to know about)
Simple Diffusion - gases, such as O2 and CO2, and small, uncharged polar molecules can cross the lipid bilayer membrane without the help of a protein
Facilitated diffusion-diffusion of polar and charged molecules, such as carbohydrates, amino acids, nucleosides, and ions, across the membrane to the other side (inside of cell). These molecules can cross the plasma membrane through USE OF A TRANSPORT PROTEIN (the proteins help, or “facilitate”)
Active Transport – REQUIRES ENERGY (ATP) because molecules are moved across the membrane against their gradient (this means molecules are going to the side of the membrane that already has more of those molecules)

13. Transport Proteins
This slide illustrates the 3 types of diffusion. Please look carefully and make sure you know and understand the differences.

14. Refer to previous illustration and plate 36 worksheet (test material)
Some proteins are only on the surface of the membrane
Attached to some of the surface proteins are carbohydrate groups that function as identification tags so cells recognize each other and do not attack each other. Find these on plate 36.
Some proteins are embedded all the way through the membrane.
Remember, proteins are made of polar (hydrophilic) and non-polar (hydrophobic) amino acids. The hydrophobic part of the protein will be next to the hydrophobic portion of the membrane. Same goes for hydrophilic. (see plate 36 illustration/text) (test material!!)

15. LE 7-7 Fibers of extracellular matrix (ECM) Glycoprotein Carbohydrate
Glycolipid
EXTRACELLULAR
SIDE OF
MEMBRANE
Cholesterol
Microfilaments
of cytoskeleton
Peripheral
proteins
Integral
protein
CYTOPLASMIC SIDE
OF MEMBRANE