1. Unit 6: Cellular Transport

2. Unit 6 Table of Contents
Lesson 6.1 – Concentration Gradients Lesson 6.2 – Active vs. Passive Transport Lesson 6.3 – Diffusion Lesson 6.4 – Osmosis Lesson 6.5 – Active Transport

3. Lesson 6.1 Concentration Gradients Learning Objectives
I can explain the concept of a concentration gradient, and identify the direction of movement along (with) a concentration gradient.

4. Molecules are always moving
Molecules move randomly and bump into each other and other barriers

5. Collision Theory
The more molecules are crowded together, in one place, the more they collide (bump into each other). As they collide, they spread out.
More collisions = more energy = higher temperatures
Fewer collisions = less energy = lower temperature

6. Concentration gradient
Concentration Gradient - change in the concentration of a substance from one area to another.
Moving “with the concentration gradient” means moving from HIGH to LOW concentration.

7. Lesson 6.2 Cellular Transport Learning Objectives
I can explain the difference between active and passive transport.

8. Cellular Transport
In order for cells to survive, they must be able to:
Move in materials which they need (nutrients, oxygen, water)
Move out materials that accumulate as toxic wastes (carbon dioxide and nitrogenous wastes) as well as chemicals made by the cell (secretion)

9. Two Types of Cellular Transport
Passive Transport:
moves materials with the concentration gradient.
Requires no energy be used by the cell.
(Diffusion, Facilitated Diffusion, and Osmosis)
Active Transport:
requires the cell to use energy (ATP)
moves materials against the concentration gradient or materials that are too large to diffuse through the cell membrane.

10. Two Types of Cellular Transport

11. Active vs. Passive Transport
DRAW this Venn diagram in your notebook. Make it nice and big (about half a page).

12. Active vs. Passive Transport

13. Active vs. Passive Transport

14. Active vs. Passive Transport

15. Active vs. Passive Transport

16. Lesson 6.3 Diffusion Learning Objectives
I can explain what a semi-permeable membrane is.
I can explain the process of diffusion and predict the direction of movement of particles in an experiment or diagram.
I can how diffusion is affected by environmental conditions such as temperature, size of particles, and concentration gradients.

17. Diffusion
Molecules in solution tend to slowly spread apart over time. This is diffusion. It is passive transport.

18. Diffusion is…
movement of molecules from an area of high concentration to an area of lower concentration. (“spreading out”)

19. Diffusion will continue until equilibrium is reached.
Equilibrium means there will be an equal distribution of molecules throughout the space.
Solute: the substance being dissolved. (Ex: Sugar)
Solvent: the substance doing the dissolving. (Ex: Water)
This is why food coloring moves throughout a beaker of water; why odors smell strong at first and then disappear over time.

20. Which direction will the molecules diffuse in each of the figures below?1 2 3 4 5 6

21. ANSWERS 1 2 3 4
No Movement 5 6
No Movement

22. Facilitated Diffusion
Uses transport/channel proteins for diffusion
Particles always move with a concentration gradient.
Passive transport.
Usually for specific molecules such as glucose.
Facilitated diffusion stops at equilibrium.

23. Lesson 6.3 Diffusion Learning Objectives
I can explain what a semi-permeable membrane is.
I can explain the process of diffusion and predict the direction of movement of particles in an experiment or diagram.
I can how diffusion is affected by environmental conditions such as temperature, size of particles, and concentration gradients.

24. Diffusion Across Selectively Permeable Membranes
The membrane is “selectively permeable”, meaning:
Not all molecules can diffuse through the cell membrane
Small molecules, like O2, CO2, and H2O CAN diffuse easily through the cell membrane.

25. Passive Transport: Diffusion Across a Selectively Permeable Membrane
Why is the
red solute
not diffusing
from the right
to the left
side?
It’s too large to
pass through
the membrane!

26. Lesson 6.3 Diffusion Learning Objectives
I can explain what a semi-permeable membrane is.
I can explain the process of diffusion and predict the direction of movement of particles in an experiment or diagram.
I can how diffusion is affected by environmental conditions such as temperature, size of particles, and concentration gradients.

27. Factors Which Affect the Rate of Diffusion:
Temperature: Higher the temperature, the higher the energy of the particles, resulting in more collisions, resulting in a higher rate of diffusion.
Concentration of Substance: The more substance present, the more collisions occur, resulting in a faster rate of diffusion.
Size of Particle: The higher the molecular or atomic mass the lower the rate of diffusion, the lower the molecular mass the faster the rate of diffusion.

28. Passive Transport

29. Amoeba Sisters Video: Cellular Transport

30. Lesson 6.4 Osmosis Learning Objectives
I can explain the process of osmosis.
I can identify hypertonic, hypotonic, and isotonic solutions, and be able to predict the direction of water movement across a semipermeable membrane.

31. Amoeba Sisters Video: Osmosis

32. Osmosis
Osmosis is the movement of WATER across a semi-permeable membrane.

33. Osmosis
Look at the diagram below:
At first the concentration of solute is very high on the right.
But over time, the water moves across the semi-permeable membrane and dilutes the particles.

34. Hypotonic = lower concentration of solute (high water)
Hypertonic = higher concentration of solute (low water)

35. Osmosis: Solutions
Isotonic = equal concentrations of solute & water on each side

36. Osmosis: Solutions

37. As viewed under the microscope
ELODEA CELLS
As viewed under the microscope

38. Lesson 6.5 Active Transport
I can explain the difference between active and passive transport
I can explain the process of exocytosis in cells.
I can explain the process of endocytosis (including phagocytosis and pinocytosis) in cells.

39. Active Transport:
Active transport requires the use of energy (ATP ) by the cell to move materials in or out.
Active transport is used when:
Moving materials against the concentration gradient
Moving ions of the same charge together
Moving large molecules

40. Active Transport: Proton Pump

41. Active Transport

42. Lesson 6.5 Active Transport
I can explain the difference between active and passive transport
I can explain the process of exocytosis in cells.
I can explain the process of endocytosis (including phagocytosis and pinocytosis) in cells.

43. Active Transport: Exocytosis
Exocytosis is the movement of materials out of the cell for secretion or to get rid of cellular waste.
It is the reverse of phagocytosis or endocytosis.

44. Lesson 6.5 Active Transport
I can explain the difference between active and passive transport
I can explain the process of exocytosis in cells.
I can explain the process of endocytosis (including phagocytosis and pinocytosis) in cells.

45. Active Transport: Endocytosis
Endocytosis is the process of taking materials into the cell that are:
too large to pass through the cell membrane (phagocytosis),
liquids that can not diffuse through the membrane (pinocytosis)

46. Active Transport: Endocytosis

47. EXO and ENDO

48. Additional Practice for Osmotic Solutions

49. Osmosis Animations for isotonic, hypertonic, and hypotonic solutions
Hypotonic: The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. (Low solute; High water)
Result: Water moves from the solution to inside the cell): Cell Swells and bursts open (cytolysis)!

50. Osmosis Animations for isotonic, hypertonic, and hypotonic solutions
Hypertonic Solution
Hypertonic: The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. (High solute; Low water)
shrinks
Result: Water moves from inside the cell into the solution: Cell shrinks (Plasmolysis)!

51. Osmosis Animations for isotonic, hypertonic, and hypotonic solutions
Isotonic Solution
Isotonic: The concentration of solutes in the solution is equal to the concentration of solutes inside the cell.
Result: Water moves equally in both directions and the cell remains same size! (Dynamic Equilibrium)

52. B C A What type of solution are these cells in? Hypertonic Isotonic
Hypotonic

53. How Organisms Deal with Osmotic Pressure
Paramecium (protist) removing excess water video
Bacteria and plants have cell walls that prevent them from over-expanding. In plants the pressure exerted on the cell wall is called tugor pressure.
A protist like paramecium has contractile vacuoles that collect water flowing in and pump it out to prevent them from over-expanding.
Salt water fish pump salt out of their specialized gills so they do not dehydrate.
Animal cells are bathed in blood. Kidneys keep the blood isotonic by remove excess salt and water.