1. Cell Membrane

2. Review of phospholipid bilayer

3. Monomers of fatty acids are used to build triacyglycerol (fats) and membrane lipids
3:12

5. Hydrophobic effect
2:20

6. A lipid bilayer prevents the diffusion of polar substances
solutes spontaneously diffuse from a region of high concentration to a region of low concentration
a lipid bilayer prevents the of polar substances of the inner compartment (also prevents the inward diffusion of polar substances)
3:13

7. Cell Membrane – fluid mosaic model
Composed of:
Lipids
double layer –
Proteins
surface
embedded proteins
Act as
Carbohydrates
Attached to surface on lipids or proteins
Many act as cards

8. Cell Membrane The cell membrane is permeable
Materials may cross the cell membrane in 3 methods:
through the membrane
Diffusion (passive transport)
Openings created via
Diffusion via channel (e.g. osmosis)
Diffusion via carrier (facilitated transport)
Carrier (active transport)
the cell membrane
Exocytosis or endocytosis (active transport)

9. Cell Membrane is Selectively Permeable

10. Transport of Molecules via Diffusion

11. Factors effecting diffusion rate
gradient
of solute molecule
of medium (solvent)
Solubility of molecule (polarity/charge)
Temperature of
stream (continuous movement of cytoplasm moves molecules around the cell)

12. Diffusion across a cell membrane
Diffusion: the of molecules from an area of concentration to an area of concentration until distributed
Diffusion is most rapid when there is a different in concentration (this is called the concentration gradient)
As the concentration decreases, the rate of diffusion
The rate of diffusion also depends on molecule and ; and the temperature and of the

13. Diffusion across a cell membrane

14. Osmosis Diffusion of H2O across a selectively permeable membrane
Every solution is made up of and the
Solute – the substance being
Solvent – the liquid that the is being dissolved within

15. Osmosis
The of water across a cell membrane depends on the type of solution (the solute of the solution) on both sides of the barrier
The tonicity ( ) of a cell can be classified by the following :
Hypotonic – a solution with a solute concentration (and so more H2O ) compared to the other solution.
Hypertonic – The solution that has a solute concentration (and so less H2O ) compared the other solution
Isotonic – the solutions have H2O concentration

16. Cells in Hypertonic Solutions
In hypertonic solutions, the of solute molecules the cell is higher than the concentration the cell
As a result, water out of the cell until equilibrium is
Cells in hypertonic solutions usually because the cells activities are by lack of
Scientific term when RBC shrinks is crenation

17. Cells in Hypotonic Solutions
In a solution, the concentration of solute molecules the cell is lower than the of solutes inside the cell
Water will therefore flow into the until equilibrium is established
The flow of water into a cell causes it to
Scientific term when water enters the RBC is hemolysis

18. Cells in Isotonic Solutions
In an isotonic solution, the concentration of solutes outside of the cell are
Water will therefore into and out of the cell at equal rates; there will be no movement of water

19. *WATER WILL ALWAYS FLOW FROM HYPOTONIC TO A HYPERTONIC SOLUTION*
Movement of Water
*WATER WILL ALWAYS FLOW FROM HYPOTONIC TO A HYPERTONIC SOLUTION*

20. : increase in vacuole's volume causes the cell membrane to
push against the cell wall

21. Transport of Molecules by Carriers

22. Facilitated Transport
Follows the gradient, so therefore, it is a passive transport

23. Facilitated Transport
Doesn’t require
Transports large molecules and charged ions since they cannot freely diffuse across the hydrophobic cell .
Carrier protein ( ) molecule in membrane is gated
CP molecule to be
CP to the molecule being
CP a conformational change and its gate opens and releases molecule to the other side
moves across the cell membrane in this manner

24. Conformational Change in Proteins

25. Active Transport
Requires energy since molecules move against the concentration gradient
Carrier protein molecule in membrane is gated
CP molecule to be transported
CP to the molecule being transported
ATP CP to open its gate to release the molecule to the side
Example: pump

26. Sodium-Potassium Pump
Will talk more about this during nervous system

27. Endocytosis and Exocytosis

28. Endocytosis Is an process and energy
Other molecules which can’t cross the cell membrane through protein channels or carriers due to their size/type enter the cell via
During endocytosis, the membrane off the cell membrane and smaller vesicle is made, which carries the material being transported in
Two types on endocytosis:

29. Phagocytosis This type of is used by the immune system cells
Large or bacteria cells are engulfed by cell membrane
Fused with to break the bacteria down

30. Pinocytosis
Other large taken in by the cell
Also known as “ ”

31. Exocytosis
Getting rid of from the cytoplasm to the exterior of the cell
Membrane of the fuses with the cell membrane and discharges its

32. What’s going on inside the cell?

33. How the fluid mosaic model is established

34. Fluid Mosaic Model
helps keep the membrane firm and prevents it from beings too fluidy
and are surface identification markers and play a role in cell-cell (what kind of cell is this? Good or bad?)
-sugar molecule attached to a phospholipid
– sugar molecule attached to a protein embedded in the membrane –

35. Proteins in the cell membrane

36. By the end of this section you should be able to:
Apply knowledge of organic molecules – phospholipids, proteins, glycoproteins, glycolipids, and cholesterol – to explain the structure and function of the fluid mosaic model
Identify the hydrophobic and hydrophilic regions of the phospholipid bilayer
Explain why the cell membrane is described and selectively permeable
Describe passive transport processes including diffusion, osmosis and facilitated transport
Explain factors that affect the rate of diffusion across a cell membrane (temperature, size of molecule, charge of molecule, concentration gradient, pressure gradient)
Predict the effects of hypertonic, isotonic and hypotonic environments on osmosis in animal cells
Describe the active transport process in terms of: concentration gradients, use of channel or carrier proteins, use of energy, types/sizes of molecules transported
Describe active transport processes such as endocytosis and exocytosis in terms of use of energy, type/size of molecules transported