1. Unit 4: Cell Membrane & Transport study Guide

2. What are two functions of the cell membrane?
Support and protect the cell
Controls what goes in and out of the cell to maintain homeostasis
2. What is the cell membrane primarily made of?
phospholipids and proteins
3. Why is the cell membrane arranged in a bilayer?
the nonpolar tails of the phospholipids are hydrophobic and repelled from water, while the polar heads are hydrophilic and attracted to water
Polar
Nonolar
Phospholipid

3. 4. How does the cell membrane help maintain homeostasis?
It makes sure that the required materials can get in and the materials that need to leave can get out
5.Why is the fluid environment of the cell and its surroundings important to its function?
The fluid environment allows materials such as nutrients, oxygen and wastes move into or out of the cell
6. What does it mean that the membrane is selectively permeable?
The membrane allows some molecules to enter the cell and keeps others out

4. 7. What are the two types of transport. Passive and active 8
7. What are the two types of transport? Passive and active 8. What are the two main differences between the two types of transport? Passive does not use energy and active does. Passive transports materials from high concentration to low while active transports from low to high concentrations. 9. What are the three types of passive transport? Diffusion, Facilitated diffusion, and osmosis 10. What are the three types of active transport? Protein pumps, endocytosis, and exocytosis

5. 11. In which type of transport do molecules move randomly. passive 12
11. In which type of transport do molecules move randomly? passive 12.In which type of transport do molecules move actively? Active 13. In passive transport, molecules move from areas of ______ concentration to areas of ________ concentration. High, low 14. In active transport, molecules move from areas of ______ concentration to areas of ________ concentration. Low, high

6. 15. What is diffusion? Random movement of particles from areas of high concentration to areas of low concentration 16. Diffusion continues until __________________ when molecules are still __________ but stay ________________. Equilibrium, moving, spread out

7. 18. How do transport proteins work?
17. What is facilitation diffusion?
Diffusion of specific particles through transport proteins found in the membrane
18. How do transport proteins work?
They “select” specific molecules to help pass through the membrane
19. What types of molecules would typically be transported by facilitated diffusion?
Large or charged particles (ex. glucose)
20. In facilitated diffusion, molecules move from areas of ______ concentration to areas of ________ concentration.
High, low

8. 21. What is osmosis? Diffusion of water through a selectively permeable membrane 22. In osmosis, _____________ moves from areas of ______ concentration to areas of ________ concentration. Water, high, low 23. Why can a cell not control the movement of water? It is so abundant and so small that it moves across the membrane out of the cell’s control 24. Define solute and solvent. Solute: what is being dissolved Solvent: what dissolves the solute

9. 25. A solution that has a lower concentration of solutes and a higher concentration of water than inside the cell is _________________. hypotonic 26. A solution that has a higher concentration of solutes and a lower concentration of water than inside the cell is _________________. hypertonic 27. A solution that has an equal concentration of solutes outside and inside the cell is _________________. isotonic

10. 28. What would happen to a cell that is placed in a hypotonic solution
28. What would happen to a cell that is placed in a hypotonic solution? Water moves into the cell and the cell swells or bursts What is that called? lysis 29. What would happen to a cell that is placed in a hypertonic solution? Water moves out of the cell and cell shrinks 30. What happens when a cell is placed in an isotonic solution? Water moves equally in and out and cell stays the same size dynamic equilibrium 31. What prevents bacteria and plant cells from over- expanding? The cell wall

11. 32. What is turgor pressure
32. What is turgor pressure? The pressure exerted on the cell wall by the water inside the cell 33. How do protists control water in their cells? The pump in or expel water with contractile vacuoles 34. How do fish control the concentration of salt in their cells? They pump salt out of their specialized gills so they do not dehydrate 35. What organs do humans use to remove excess salts and water? kidneys

12. In what type of solution is the cell? Hypotonic
36. A cell has 20% salt and 80% water is in a solution that has 10% salt and 90% water.
In what type of solution is the cell?
Hypotonic
b. Where will water move?
Into the cell
c. What will happen to the cell?
It will lyse (cell swell and/or burst)
20% Salt
80% Water
10% Salt
90% Water

13. In what type of solution is the cell? Hypertonic
37. A cell has 20% salt and 80% water is in a solution that has 30% salt and 70% water.
In what type of solution is the cell?
Hypertonic
b. Where will water move?
Out of the cell
c. What will happen to the cell?
Cell will shrink
20% Salt
80% Water
30% Salt
70% Water

14. 38. A cell has 20% salt and 80% water is in a solution that has 20% salt and 80% water. a. In what type of solution is the cell? Isotonic b. Where will water move? In and out of the cell equally c. What will happen to the cell? It will reach dynamic equilibrium and stay the same size
20% Salt
80% Water
20% Salt
80% Water

15. Sodium Potassium Pumps (Active Transport using proteins)
39. What are protein pumps? Transport proteins within the cell membrane that require energy to do work 40. Give an example of a protein pump. Sodium/potassium pump 41. Protein pumps change _________ and require __________. Shape, energy 42. Protein pumps move molecules from areas of ______ concentration to areas of ________ concentration. Low, high
Sodium Potassium Pumps (Active Transport using proteins)

16. Endocytosis & Exocytosis animations
43. What is endocytosis? Taking bulky material into a cell 44. Describe the process cells use to “eat”. Cell membrane folds around a food particle and forms a food vacuole where the food is digested 45. What is exocytosis? Membrane around the material fuses with the cell membrane and forces the material out of the cell 46. What types of materials are commonly expelled by exocytosis? Hormones, waste
Endocytosis & Exocytosis animations

17. 47. Why does active transport require more energy than passive transport? Passive transport goes with the concentration gradient while Active transport goes against the concentration gradient. Going against the gradient (low  high) requires energy.
Diffusion
Hypertonic
Isotonic
Hypotonic