1. Moving Through the Plasma Membrane

2. Let’s Review What is homeostasis?
What is the job of the plasma membrane?
How do you think the cell membrane helps a cell maintain homeostasis?

3. Structure and Function
Phospholipid bilayer with carbohydrates and proteins imbedded into itself
Brings in essential materials and excretes waste products

4. What does a phospholipid look like?
Polar head/ hydrophilic
Nonpolar head/ hydrophilic

6. What does the Plasma Membrane look like?
Outside Cell (Extracellular Matrix)
Protein
Glycoprotein
Phospholipids
Cholesterol
Inside Cell (Cytoplasm)

7. The Plasma Membrane Polar Non-Polar
Outside Cell (Extracellular Matrix)
Protein
Glycoprotein
Phospholipids
Cholesterol
Inside Cell (Cytoplasm)

8. Plasma Membrane: The Fluid Mosaic Model

9. Plasma Membrane: The Fluid Mosaic Model
Fluid because
the phospholipid and protein molecules are able to move around. Not stuck in one place.
Mosaic because
the membrane contains a variety of proteins embedded with the phospholipids.

10. How do particles move in and out of the cell?

11. Permeability of a membrane
Permeable: anything can pass through
Semi-permeable: some things can pass through
Impermeable: nothing can pass through

12. The plasma membrane is described as semi-permeable because some substances can move through it:
Small and
Non-polar

13. Passive Transport energy
No additional _______________ is required because every particle has its own energy
This energy produces ________________ movement in particles. (a.k.a Brownian motion)
random

14. Diffusion area high Brownian Motion
Diffusion is the movement of substances from a ________ concentration to a low concentration.
Diffusion is caused by ______________________
Concentration is the _________ of something in a given ______.
high
Brownian Motion
amount
area

15. Examples of diffusion at work
Why does food smell fragrant when cooked?
Have you ever stood next to someone wearing strong perfume?

16. How does it work?
Particles move down the concentration gradient, until the concentration is _________ throughout an area.
Then the system is said to have reached dynamic equilibrium.
equal

17. A. B. High Concentration of Orange Dots
Low Concentration of Blue Dots
High Concentration of Blue Dots
Low Concentration of Orange Dots B.
System has reached dynamic equilibrium

18. Back to the plasma membrane…
Outside Cell (Extracellular Matrix)
Inside Cell (Cytoplasm)

19. Osmosis
Diffusion of _________ across a membrane
Water molecules can pass through pores or openings created by __________ in the plasma membrane .
water
proteins

20. Back to the plasma membrane…
Outside Cell (Extracellular Matrix)
Protein
Glycoprotein
Phospholipids
Cholesterol
Inside Cell (Cytoplasm)

21. The Cell’s Environment: Isotonic
In an isotonic environment the solute concentrations are ___________ and there is no NET movement of water.
equal

22. The Cell’s Environment: Hypotonic
In a hypotonic environment, there are __________ solutes outside than inside and water moves into the cell.
less

23. The Cell’s Environment: Hypertonic
In a hypertonic environment there are _________ solutes outside than inside and water moves out of the cell.
more

24. Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic
Hypertonic
Isotonic

25. Environment outside cell Water moves… Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In
Swells, then bursts (cytolysis)
Hypertonic
Isotonic

26. Animal Cell Cytolysis
Cells burst
Cell still intact

27. Swells, then bursts (cytolysis) Swells, increases turgor pressure
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In
Swells, then bursts (cytolysis)
Swells, increases turgor pressure
Hypertonic
Isotonic

28. Swells, then bursts (cytolysis) Swells, increases turgor pressure
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In
Swells, then bursts (cytolysis)
Swells, increases turgor pressure
Hypertonic
Out
Isotonic

29. Swells, then bursts (cytolysis) Swells, increases turgor pressure
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In
Swells, then bursts (cytolysis)
Swells, increases turgor pressure
Hypertonic
out
Shrinks (crenation)
Isotonic

30. Swells, then bursts (cytolysis) Swells, increases turgor pressure
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In
Swells, then bursts (cytolysis)
Swells, increases turgor pressure
Hypertonic
out
Shrinks (crenation)
Shrink (plasmolysis)
Isotonic

31. Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In
Swells, then bursts (cytolysis)
Swells, increased turgor pressure
Hypertonic
Out
Shrinks
(crenation)
Shrinks, (plasmolysis)
Isotonic

32. Swells, then bursts (cytolysis) Swells, increases turgor pressure
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In
Swells, then bursts (cytolysis)
Swells, increases turgor pressure
Hypertonic
out
Shrinks (crenation)
Shrink (plasmolysis)
Isotonic

33. Plant cell: Plasmolysis
Plasmolyzed
Cells
Normal cells

34. Swells, then bursts (cytolysis) Swells, increases turgor pressure
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In
Swells, then bursts (cytolysis)
Swells, increases turgor pressure
Hypertonic
out
Shrinks (crenation)
Shrink (plasmolysis)
Isotonic
In and out at the same rate

35. Swells, then bursts (cytolysis) Swells, increases turgor pressure
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In
Swells, then bursts (cytolysis)
Swells, increases turgor pressure
Hypertonic
out
Shrinks (crenation)
Shrink (plasmolysis)
Isotonic
In and out at the same rate
Stays the same

36. Swells, then bursts (cytolysis) Swells, increases turgor pressure
Environment outside cell
Water moves…
Effect on ANIMAL cell
Effect on PLANT cell
Hypotonic In
Swells, then bursts (cytolysis)
Swells, increases turgor pressure
Hypertonic
out
Shrinks (crenation)
Shrink (plasmolysis)
Isotonic
In and out at the same rate
Stays the same

38. Osmosis in Action What happens when you sprinkle salt on a slug?
If you are stranded at sea and run out of water, should you drink sea water?
** Water moves from a hypo to a hypertonic environment.

39. True or False
In diffusion, particles move from an area of high to low concentration.
Diffusion does not require any additional energy to occur.
Small, charged or polar particles can move through the cell membrane by simple diffusion.

40. What if a cell needs large or charged/ polar molecules
What if a cell needs large or charged/ polar molecules. Can they move across the membrane?
Yes!

41. Selectively Permeable Membrane
The cell membrane “picks” what molecules can enter and exit the cell because proteins in the membrane allow specific macromolecules or ions in or out of the cell.

42. Facilitated diffusion
Proteins help particles move across the membrane
Transport proteins span the phospholipid bilayer, but allow only ___________ molecules through.
>> Selectivity
specific

43. Types of transport proteins
Ion channels
____ __________ are non–polar on the outside and polar on the inside. They provide a pore for ions and polar particles to move through.

44. Carrier Proteins
_________ _______________ bind to specific particles, carry them through the membrane, and release them on the other side.

45. Remember!
In diffusion-particles (solutes) move from an area of HIGH concentration to LOW In osmosis- water moves from a HYPOTONIC environment to a HYPERTONIC environment
Diffusion requires NO energy input

46. Simple vs. Facilitated
In simple diffusion, particles move between phospholipid molecules of the membrane.
In facilitated diffusion, particles move through transport proteins in the membrane.
Both do NOT use energy. Particles must move down the concentration gradient.

47. But what if you needed to move particles against their concentration gradient?

48. Active Transport
Transport proteins use ________to move particles against their concentration gradient, from a low concentration to a high concentration.
energy

49. Sodium-Potassium Pump:
Carrier- protein that pumps 3 sodium ions (Na+)________ the cell, while pumping 2 potassium ions (K+)________.
outside
inside

50. 3 Na+ ions from inside the cell bind to the pump protein
3 Na+ ions from inside the cell bind to the pump protein. Energy from ATP is added to the protein.
The Na+ ions are moved to the outside of the cell.
The 3 Na+ ions are released and 2 K+ ions bind to the protein.
The protein changes back and releases the 2 K+ ions into the cell.

51. Vesicle Mediated Transport
The fluid plasma membrane can “pinch” off forming vesicles that can move very _______particles or lots of ______particles.
This process needs _______.
large
small
energy

52. Endocytosis Outside materials are brought __________ the cell. inside
3) Vesicle with food
1) Food particle
2) Pouch forming around food

53. Endocytosis Phagocytosis “Cell eating”
Cell engulfs large food particles and the vesicle is a food vacuole.
Pinocytosis
“cell drinking”
Cell engulfs small droplets of surrounding fluid.

54. Exocytosis
Material from inside the cell is released _________ by vesicles.
outside
1) Vesicle fuses with membrane
3) Particle released
2) Pouch opens