1. Transport of Materials
Unit 3
Transport of Materials

2. Key Questions 1. Why must materials enter and leave cells?
What materials need to enter and leave cells?
What role does the cell membrane play in the transport of materials into and out of a cell?
How do materials get into and out of a cell?
How do materials move within a cell?

3. 1. Why must materials constantly enter and leave cells?
Transport
1. Why must materials constantly enter and leave cells?

4. Transport
Cells must maintain a constant internal environment (homeostasis)
So, materials (nutrients and wastes) must constantly move in and out of the cell and throughout the cell.

5. Transport
2. What materials need to enter and leave cells?

6. Transport Examples of substances entering a cell:
Nutrients
Salts
Oxygen
Water
Examples of substances leaving a cell:
Wastes
Carbon dioxide
Synthesized molecules

7. Transport
3. What role does the cell membrane play in the transport of materials into and out of a cell?

8. Transport Cell Membrane: The cell membrane is selectively permeable
The cell membrane regulates/controls what is transported into (absorption) and out of the cell

10. Cell Membrane
Certain substances can pass through the membrane more easily than others,
Small molecules pass easily (ex.: water, glucose, amino acids, carbon dioxide, oxygen)
Large molecules cannot pass easily (ex.: starch, proteins)

11. Cell Membrane
That is why they get broken down during DIGESTION!!!

12. Cell Membrane
Absorption is when nutrients (like glucose and oxygen) are taken into a cell
The cell membrane has a large surface area in order for the absorption of nutrients to occur

13. Transport
How do materials get into and out of a cell?
DEMO-room spray

14. Transport
By diffusion/osmosis or active transport!!!

15. 1. Diffusion/Osmosis
Does NOT require ENERGY to move materials into and out of the cell.

16. Diffusion
Movement of molecules from a high concentration to a low concentration due to a concentration gradient.
Concentration Gradient – difference between high and low

17. Diffusion Occurs because the molecules are constantly moving.
Continues until equilibrium is reached – when the molecules are distributed evenly.

19. Diffusion Animation
hill.com/sites/ /student_view0/chapter 2/animation__how_diffusion_works.html

20. Balloons and Diffusion
Why do helium balloons sink over time?
DEMO:
Why can you smell the flavor through the balloon?

21. 2. Osmosis
The diffusion of water molecules through a semi-permeable membrane
Occurs from an area with a high concentration of water molecules to an area with a low concentration of water molecules

22. DEMO: Beaker and food coloring!

24. Effects of Osmosis on Cells
Isotonic Solution:
Concentration of water molecules inside the cell and in an isotonic solution solution is the same
No concentration gradient, so cell doesn’t gain or lose water

26. Isotonic Solution - Animal Cell

27. Isotonic Solution – Plant Cell
Solute concentration inside the cell is equal to outside

28. Effects of Osmosis on Cells
Hypotonic Solution
Larger concentration of water molecules outside the cell
Solution has less dissolved materials than the cell
Water moves into the cell by osmosis and animal cells swell and could burst

29. Hypotonic Solution – Animal Cell

30. Hypotonic Solution – Plant Cell

31. Effects of Osmosis on Cells
Hypertonic Solution
Larger concentration of water molecules inside the cell
Solution has more dissolved materials than the cell
Water moves out by osmosis and animal cells shrink

32. Hypertonic Solution – Animal Cell

33. Hypertonic Solution – Plant Cell

34. Osmosis Vocab for Plant Cells
Turgor Pressure
Pressure on cell wall caused by increased expansion of water in vacuole from osmosis
The rigid cell wall prevents cell from bursting
Plasmolysis
When in hypertonic solutions, cell membrane pulls away from cell wall due to water loss by osmosis

35. 2. Active Transport
Processes that do require use of energy to move materials into and out of cells
Important in movement of molecules into and out of cells

36. Active Transport
Move materials from a high concentration to a low concentration OR from a low to a high concentration (against concentration gradient)
Moves larger molecules

37. FYI – Types of Active Transport
1. Membrane/Transport Pump
Carrier proteins are used to pick up ions or molecules near the cell membrane, carry them across the membrane, and release them on the other side.

39. Types of Active Transport
2. Endocytosis/ Exocytosis
Cell membrane folds in and forms a small pouch
Pouch releases the contents inside the cell
Exocytosis is the opposite

41. Inside the Cell
Once materials are inside the cell, they can move throughout by:
Diffusion in the cytoplasm
Cyclosis – streaming of the cytoplasm – to move materials throughout the cell
And the endoplasmic reticulum and golgi body

42. Cyclosis in Plant Cells

44. NY State Required Lab-Diffusion Through a Membrane
Objectives – Week 1:
Testing with chemical indicators
Understanding diffusion (size of molecules)

46. Results-part 1 Explain the ‘final state.’’
Which molecules diffused and why?
Which molecules did not diffuse and why?

47. Part 2-Osmosis Objectives:
Explain what happens when cells are placed in solutions having different concentrations
Explain osmosis

49. Explain what happened to the cells and why.

50. Applicable NY State Standards
1.2g, 1.2h, 1.2i