1. Cell Membrane & THE WAYS MOLECULES MOVE Chapter 7-3
Cellular Membrane & Transport (Ch. 7-3)
Cell Membrane & THE WAYS MOLECULES MOVE Chapter 7-3
Cellular Membrane & Transport (Ch. 7-3)

2. Cellular Membrane & Transport (Ch. 7-3)
Cell Membrane
1) POLAR ends face INSIDE & OUTSIDE cell (where water is…Hydrophilic)
2) NONPOLAR tails face each other inside bilayer (to avoid water…Hydrophobic)
Cellular Membrane & Transport (Ch. 7-3) 2

3. Cellular Membrane & Transport (Ch. 7-3)
Outside
of cell
Inside
(cytoplasm)
Cell
membrane
Proteins
Protein
channel
Lipid bilayer
Carbohydrate
chains
Cellular Membrane & Transport (Ch. 7-3)
Cellular Membrane & Transport (Ch. 7-3) 3 3

4. Cellular Membrane & Transport (Ch. 7-3)4 4

5. Cellular Membrane & Transport (Ch. 7-3)
3) FUNCTION: SELECTIVE PERMEABILITY = allows only certain materials to go into & out of cell
Cellular Membrane & Transport (Ch. 7-3) 5 5

6. Cellular Membrane & Transport (Ch. 7-3)
* Why doesn’t the cell membrane let everything through?
HOMEOSTASIS!
- Cells maintain a stable environment by controlling what enters & leaves.
Cellular Membrane & Transport (Ch. 7-3) 6

7. Diffusion

8. FROM A LOT to NOT Molecules move _______“where there’s _______”

9. DIFFUSION across a space
Happens anytime there is a __________ in concentration in one place compared to another
= ________________________
DIFFERENCE
Concentration gradient

10. DIFFUSION across a SPACE
Molecules move automatically _______ the concentration gradient _______ an area of _______ concentration ____ an area of ________ concentration
EXAMPLES
DOWN
from
Higher to
Lower
Blue dye in beaker demo,
Someone making popcorn/grilling out
Strong perfume,
Bad smell in room

11. DIFFUSION across a space
Diffusion continues until the concentration is ________________ in space
= ________________________
equal everywhere
Equilibrium

12. Molecules need to move across membranes in cells

13. Diffusion can happen ________ a _____________ in a cell, too
across
membrane
…as long as membrane will let the molecule _________________
pass through

14. CELL EXAMPLE:
DIFFUSION automatically moves oxygen from HIGHER concentration (in lungs) to a LOWER concentration (in blood)
CO2 automatically moves from where there is a
HIGHER concentration
(in blood) to where there
is a lower concentration
(in lungs)

15. PROBLEM for CELLS? Diffusion only moves molecules from high concentration to low concentration.

16. What if cell needs to move a molecule _________ the CONCENTRATION GRADIENT? _______________
AGAINST
(LOWER  HIGHER)
Cell example:
Want to put MORE glucose
into mitochondria when there is
already glucose in there

17. PROBLEM for Cells? Cell membranes are SELECTIVELY PERMEABLE
See a movie

18. What if a cell needs to move _____ or ______ molecules that can’t get through the membrane?
LARGE
POLAR

19. PROBLEM for CELLS? Diffusion happens very slowly

20. What if cell needs to move molecules really _______
What if cell needs to move molecules really _______? (can’t wait for it to diffuse)
FAST
Cell example:
Movement of Na + & K+ ions
required to send
nerve signals

21. Cells need a ____ to ____ molecules across cell membranes that _______ across by ___________
WAY
HELP
can’t go
themselves

23. Kinds of ________ Transport
PASSIVE
__________________________________
___________________________________
_______________________________
Diffusion
Facilitated Diffusion
Carriers
Channels

24. DIFFUSION across a membrane
DIFFERENCE
Happens anytime there is a __________ in _____________ on one side of the membrane compared to the other
concentration
See diffusion animation

25. DIFFUSION PASSIVE DOWN HIGHER to LOWER OXYGEN Carbon dioxide
No energy required = _______
Moves _______ concentration gradient
from ___________________
Works for any molecules that can pass through the membrane
Example of molecules that move this way in cells:
________ & ____________
DOWN
HIGHER to LOWER
OXYGEN Carbon dioxide

26. FACILITATED DIFFUSION uses _______________ to help molecules across 2 kinds of proteins help: _________ & ____________
membrane proteins
Carriers
Channels

27. Facilitated Diffusion with CARRIER PROTEINS
grabs molecule,
changes shape, and
flips across to
other side like a
revolving door

28. FACILITATED DIFFUSION with CHANNELS
Membrane
proteins
create a
tunnel through
which molecules
can pass
ION CHANNELS
charged
_______________ allow________ ions to get past the ____________ center
hydrophobic

29. FACILITATED DIFFUSION with CHANNELS
polar
________ proteins allow ________
_________ molecules to get past
the __________ middle of cell
membrane.
Aquaporin
WATER
hydrophobic

30. FACILITATED DIFFUSION with CHANNELS
The movement of water molecules
across a cell membrane is called
______________
OSMOSIS

31. ALL KINDS OF FACILITATED DIFFUSION
PASSIVE
No energy required = _____________
Moves ________ concentration gradient
from ________________________
___________________ help molecules get across membrane
DOWN
HIGHER to LOWER
Membrane proteins

32. EXAMPLES OF FACILITATED DIFFUSION IN CELLS
CARRIER PROTEINS
ION CHANNELS
AQUAPORINS (OSMOSIS)
GLUCOSE
Na+ , Cl- , Ca++ , K+
WATER

34. Kinds of ________Transport
ACTIVE
________________________________________
__________________________________
________________________________
___________________________________
PUMPS
Sodium-Potassium
Proton
Vesicles
Endocytosis
Exocytosis

35. Na+ and K + PUMP
See a movie about Na+ - K+ pump

36. SODIUM-POTASSIUM PUMP
ACTIVE
___________ transport
(requires energy from ______)
Can move molecules from _____ concentration
to ______
Special just for Na+ and K + ions
Uses _______________________ called ____________ to move molecules
Example: nerve cells Na+ is pumped out of cells at same time K + is taken into cells
ATP
low
high
membrane proteins
pumps

37. PROTON PUMP H+ Moves Protons across membrane = ___ ions
See a movie proton pump
More on this in Chap 8 & 9

38. PROTON PUMP ACTIVE ATP low high Protein pumps ___________ transport
(requires energy from ______)
Can move molecules from _____ concentration to ________
Special just for H+ ions
Uses integral ________________ to move molecules
Examples:
Lysosomes need acidic conditions for digestion
Photosynthesis/Respiration (more on this to come in Ch 8 & 9)
ATP
low
high
Protein pumps

39. ACTIVE TRANSPORT with VESICLES
___________ are small membrane sacs that pinch off of cell membranes used by cells for transporting molecules
Used for transporting molecules:
If entering the cell = ______________
If exiting the cell = _______________
ENDOCYTOSIS
EXOCYTOSIS

40. 2 KINDS of ENDOCYTOSIS for taking substances into cell
If taking in:
fluid or small molecules =_________________
large particles or whole cells =______________
PINOCYTOSIS
PHAGOCYTOSIS
Animation from:

41. ENDOCYTOSIS Substances taken into cell
ACTIVE
energy
__________ transport (requires________)
Uses ______________ to carry substances
Can move molecules from _____ concentration
to ______
Examples in cells:
one celled organisms eat this way
white blood cells get rid of bacteria this way
VESICLES
low
high

42. ENDOCYTOSIS
Protist eating
another

43. PHAGOCYTOSIS
White blood cell
germs
___________ destroying _______

44. WHITE BLOOD CELL ENGULFING BACTERIA (Phagocytosis)

45. EXOCYTOSIS Substances released outside of cell
ACTIVE
energy
__________ transport (requires________)
Uses ______________ to carry substances
Can move molecules from _____ concentration
to ______
Examples in cells:
_________ release packaged proteins this way
VESICLES
low
high
GOLGI

46. GOLGI BODIES USE EXOCYTOSIS
See a Golgi movie

47. INSULIN being released by pancreas cells using exocytosis

48. VOCAB
_____________ = substance that is dissolved in a solvent to make a solution
_____________ = substance in which a solute is dissolved
SOLUTE
SOLVENT

49. __________________ = mass of a solute in a given volume of solution
CONCENTRATION
MORE
The _______ molecules there are in a given volume the ____________the concentration
GREATER

50. Use new vocab to make Koolaid
Koolaid powder
sugar
Solutes = ______________& __________
Solvent = ____________
Koolaid drink = ______________
Water
solution

51. What if there is a difference in concentration but solute molecules can’t move across a membrane?
WATER will move
until concentration
reaches equilibrium

52.  See an animation Osmosis1

53. What will happen to an animal cell placed in different solutions?
Solute concentration
Greater outside
than inside
Lower outside
than inside
Equal outside
and inside
HYPERTONIC
HYPOTONIC
ISOTONIC
What will happen to an animal cell
placed in different solutions?

54. Cells try to “maintain stable internal conditions =
Remember:
Cells try to “maintain stable internal conditions =
____________________
HOMEOSTASIS
So an animal cell in
ISOTONIC conditions
stays same size
Water entering = water leaving
Video
Choose Blood Isotonic link

55. If cells can’t maintain
“stable internal conditions” . . .
damage can result and cells can die.

56. OSMOSIS swell and possibly burst Video LESS THAN
See an animation Osmosis3
Video
Choose Blood
Hypotonic link
HYPOTONIC: Concentration outside cell is ________________ inside the cell More water enters than leaves cell so cell will ___________________
LESS THAN
swell and possibly burst

57. OSMOSIS shrinks GREATER THAN Video
See an animation
OSMOSIS 4
HYPERTONIC: Concentration outside cell is ____________________ inside cell
More water leaves cell than enters so cell ____________
GREATER THAN
shrinks
Choose Blood
Hypertonic link
Video

58. Animal cells
_________ __________
= CYTOLYSIS
= CRENATION

59. Plant cells _____ keeps ___________ = PLASMOLYSIS CELL WALL
plant cells from bursting
= PLASMOLYSIS
CELL WALL

60. VACUOLES store WATER OSMOTIC PRESSURE _____________________________ =
_____________________________ =
Pressure exerted by the movement of water during osmosis

61. SO WHAT? hypotonic Bath water is ________________ compared to you
Sitting in the bathtub causes your fingers and toes to wrinkle up when water ________ your skin cells by osmosis
enters

62. Grocery stores spray water on their veggies to “plump them up”