1. The Plasma Membrane Thickness of 7 - 8 nm
You would need membranes
to add up the thickness of one sheet of paper

2. The Plasma Membrane Function: Structure:
Selective passage of certaine substances during transport through the membrane
Structure:
Lipid bilayer
A) phospholipis
B) cholesterol
C) glycolipids
Proteins
Cholesterol

3. Lipid bilayer
cholesterol
phospholipids
glycolipid

4. phospholipids Structure: Hydrophilic Region Polar head
Oriented towards the aquatic region
Hydrophobic Region
Non-polar Tails
Oriented towards the inside of the bilayer
Functions:
Fluidity of the membrane
Selective permeability

5. Unsaturated fatty acids
phospholipid
Formation
Saturated fatty acids
tail
Unsaturated fatty acids
tail
Right
Is Bent

6. Properties of the phospholipids
Repair: If the membrane is pierced, the separated molecules of phospholipids can come together and close the opening.
Modification: The molecules of phospholipids can add more phospholipids or take some away to change the volume of the cell.
Division: During division, the center of the cell can separate and form two cells. Two cells can also join together to create one.

7. Properties of phospholipids
Selective Permeability:
Permeable: To lipo-soluble molecules, and to very small molecules (O2 et CO2)
Impermeable: Big molecules, and to ions (K+ , Na+, Cl -)

8. Le cholestérol représente
Cholesterol
Functions:
Reduce the fluidity of the membrane
Stabilise the membrane
Increase the rigidity of the membrane.
Situated between the molecules of phospholipids in the bilayer.
Le cholestérol représente
de 15 à 50% des lipides

9. Glycolipid/ Marker Glyco for glucose = sugar Lipid = fatty acid
Participates in the formation of glycolipids
The glycolipds are situated on the external surface of the membrane
Functions:
Gives a cellular identity
Permits cellular adherence (stick together)

10. Proteins 3 types: Marker (Glycoproteins):
glucose chaine attached on a protein
Receptor (hormone):
Receives instructions, communication
TRANSPORT PROTEINS
Carrier Proteins (Peripheral proteins) :
placed one next to the other in the bilayer
Channel (Intrinsic proteins) :
extends through the bilayer

11. Functions of the proteins
Canal: permits the passage of certain substances across the membrane
Transporter: transports molecules from one side to the other
Receptor: recognizes specific substances and modifies the activities of the cell. Receives instructions.
Recognition: Gives a cellular identity.
Adherence: Permits cellular adherence (stick together), which increases stability

12. Fluid mosaïc Model
Mosaïc: the composition of the membrane is heterogenous (not the same)
Fluid: the molecules move: laterally (~107 times/seconde), they rotate and flip-flop (~ 1 time/month)

13. Functions of the Cell Membrane
Selective passage of substances
across the membrane
Passive Transport
Active Transport
Diffusion
(Simple or
passif)
Osmosis
Pump
Exocytosis
Facilitated
Diffusion
Endocytosis