Unit 5:Cell Membrane and Transport

Review

1. Difference between polar and nonpolar compounds? Give an examples.• Polar

– dissolve in water, Hydrophilic, have one positive side and one negative side;

– Examples: water, sugars, ionic compounds, phosphate head of phosopholipid

• Nonpolar – don’t dissolve in water, Hydrophobic, No charges on molecule– Examples: lipids, lipid tail

2. What is an aqueous solution? • A solution where water is the solvent- Solute – dissolved particles (salt, sugar)- Solvent – Substance that is doing the dissolving (water)

3. What does selectively permeable mean?• Only certain material can cross through the cell membrane

4. What does the term “phospholipid bilayer” mean? - Two layers of phospholipid molecules (makes up cell membrane)

5. Diff between a hydrophobic and a hydrophilic molecule? Give examples. – Hydrophobic: “Water Hating”, nonpolar, no charges, does not dissolve in

water, does not interact with water, repels water• Example: Lipids, Lipid tail of phospholipid

– Hydrophilic: “Water Loving”, polar, may have a charge (ions), can dissolve in water, interacts with water• Example: Phosphate head of phospholipid, water, carbohydrates

6. What molecules can cross through the cell membrane without assistance?– Small, uncharged molecules that can squeeze between the phospholipids

and are soluble in lipids (can cross through lipid tail)

7. What molecules need help crossing the cell membrane?– Large molecules that cannot squeeze through the membrane– Charged particles that can’t pass through lipid middle (not soluble in lipids)

8. Briefly describe the function of each part of the cell membrane.– Phospholipid:

• Function: Makes up the majority of the cell membrane, helps make membrane “fluid” and selectively permeable

• In a bilayer; Phospholipids not connected/bonded to each other• Hydrophilic phosphate heads face external and internal cell

environment• Hyrdrophobic lipid tails face towards middle section of membrane

– Cholesterol – helps to make membrane “fluid”/flexible– Peripheral protein – helps keep shape of cell & attaches cell membrane

to the cytoskeleton (keeps membrane attached to cell contents)– Integral protein – channel used for certain molecules to cross through

the membrane– Glycoprotein – used as a cell recognition (ID) and receptor (mailbox)

• Integral protein with a glycogen (carbohydrate) attached to part of protein that faces the external cellular environment (outside cell)

9. Difference between passive and active transport? List the types of each.• Passive:

– Molecules moving from high concentration to low concentration– Moving “Down the Gradient”– Natural movement of molecules– Does not require energy (ATP) to occur– Examples: Diffusion, Osmosis, Facilitated Diffusion, Ion Channel

• Active:– Molecules moving from a low concentration to high concentration– Moving “Up the Gradient”– Goes against natural flow of molecules– Requires energy (ATP) to occur– Examples: Membrane Pump (Sodium-Potassium Pump), Endocytosis

(Pinocytosis, Phagocytosis), Exocytosis

10. CONCENTRATION GRADIENT – when the solutions on either side of the membrane do not have the same concentration of solutes (one more concentrated than the other)

11. EQUILIBRIUM – When the concentration is equal throughout the space/solution

12. DIFFUSION - Movement of molecules from an area of high concentration to an area of lower concentration, type of passive transport

13. OSMOSIS – diffusion of water, type of passive transport

14. TURGOR PRESSURE – internal pressure in a plant cell, occurs when vacuole is full of water, cell in hypotonic solution

15. CYTOLYSIS – when a Red Blood Cell (RBC) bursts due to cell taking in too much water (cell in hypotonic solution)

16. PLASMOLYSIS – when a plant cell becomes shriveled due to cell losing too much water (cell in hypertonic solution)

17. CRENATION – when a RBC becomes shriveled due to losing too much water (cell in hypertonic solution)

18. CARRIER PROTEIN – part of cell membrane, integral protein, functions to help large, bulky, or polar molecules across membrane from high to low concentration, type of passive transport, doesn’t need ATP, (Facilitated Diffusion)

19. ION CHANNEL – part of cell membrane, functions to help ions (charged atoms) across the membrane from high to low concentration, type of passive transport, doesn’t need ATP

20. MEMBRANE PUMP – part of cell membrane, integral protein, functions to pump molecules from a low to high concentration, pumps molecules against the gradient, requires ATP, active transport, Ex: Sodium-Potassium pump

21. ENDOCYTOSIS – type of active transport, requires ATP, makes huge structural changes in shape of cell membrane, how cells ingest large amounts of substances

22. PINOCYTOSIS – type of active transport, type of endocytosis, requires ATP, cells ingest fluid

23. PHAGOCYTOSIS – type of active transport, type of endocytosis, requires ATP, cells ingest solid particles

24. VESICLE – specialized organelle used to transport material throughout the cell

25. EXOCYTOSIS – type of active transport, type of endocytosis, requires ATP, how cells expel particles

Hypotonic Solution • Explain Solution:

– More water outside the cell (less water inside the cell)– Higher concentration of water outside cell– Less solutes outside cell, more solutes inside cell

• Example: Distilled water (higher % of water or lower % solutes)

• What happens to cell:– More water moves into the cell– Water diffuses into the cell– Cell could burst – Cytolysis– Cell could get full vacuole & added support – Turgor Pressure

Hypertonic Solution• Explain Solution:

– Less water outside the cell (More water inside cell)– Lower concentration of water outside cell– Less solutes inside cell, more solutes outside cell

• Example: Corn syrup, Salt water (lower % of water or higher % of solutes)

• What happens to cell:– More water leaves the cell– Water diffuses out of the cell– Cell could shrivel

• Crenation – Red Blood Cell • Plasmolysis – Plant Cell

Isotonic Solution• Explain Solution:

– Equal concentration of water inside and outside of the cell– Equal concentration of solutes inside and outside of the cell– Cell is in equilibrium

• Example: Tap water, Saline solution (equal % of water, equal % of solutes)

• What happens to cell:– Water moves into and out of the cell at the same rate– Cell does not change in shape or size