Cell Membrane and Transport Study Guide

1. Draw a box around one phospholipid. 2 1. Draw a box around one phospholipid. 2. Label the brackets as being either hydrophobic region or hydrophilic region. 3. Label all the leader lines with the following terms: carbohydrate side chain marker protein channel protein Channel protein Carbohydrate side chain hydrophilic hydrophobic Marker protein

semi – permeable 4. The plasma or cell membrane is considered _____ _________ because it regulates what enters and leaves the cell. 5. The monomers that make up a phospholipid are ____________ group attached to a ______________ molecule and two _____ _____ tails. 6. The phosphate heads are _________________ (water-loving). 7. The fatty acid tails are _______________ (water-hating) 8. Because of this property, phospholipids form ____ layers in water, with the hydrophobic tails facing ____ and the hydrophilic heads facing the ______________. phosphate glycerol fatty acid hydrophilic hydrophobic two in water (out)

Things that can dissolve in fat Things that are small Water 9. Due to the membrane’s hydrophobic and fatty properties, the cell membrane allows the following items to pass through: Things that can dissolve in fat Things that are small Water 10. Charged molecules or ________ cannot penetrate the hydrophobic core because it is ________________ (water-loving). Things that are too __________ in size also cannot pass through the core, unless it is assisted by a _____________ protein. ions hydrophilic large channel

Passive vs. Active Does not use energy Moves molecules from high to low concentration Molecules move down the concentration gradient Substances reach equilibrium Uses energy Moves molecules from low to high concentration Molecules move up or against the concentration gradient Stockpiles or stores substances Both transport substances across the membrane

12. List three types of passive transport: Simple Diffusion b. Osmosis c. Facilitated Diffusion   13. Draw arrows in the diagram to the right, indicating the direction in which the particles move across the membrane via diffusion.

14. What is osmosis? The diffusion of water across a membrane from an area of high concentration to an area of lower concentration.

15. In the image to the right, draw an arrow indicating the movement of water molecules through the membrane via osmosis. 16. The glucose in the image to the right is too big to pass through the membrane. However, if it were to be “assisted” across the membrane by a channel protein, this process would be called ___________ ________. faciitated diffusion

17. List three types of active transport: a. Protein pumps b. Exocytosis c. Endocytosis 18. Which letter(s) to the right best represents active transport? C  19. Which letter(s) to the right best represents passive transport? A and B

20. The energy that the cell uses for active transport is called __ __ __   21. Why might material need energy to move through the cell membrane? a. It needs to store or stockpile material in high concentrations b. It needs to physically move the membrane to engulf a substance. Movement requires energy. A T P

22. Draw arrows in the diagram to the right, indicating the direction in which the particles move across the membrane via active transport. 23. Name two ways in which a particle that is too large to fit through the cell membrane can still enter the cell? Facilitated Diffusion Endocytosis

24. Which diagram to the right represents exocytosis? B 25. Which diagram to the right represents endocytosis? A A B

26. Explain what is happening in the diagram through the process of endocytosis and distinguish between phagocytosis and pinocytosis. Endocytosis is the process where the cell wraps it’s membrane around a substance and engulfs or swallows that substance, creating a vesicle. Phagocytosis is the engulfing of large substances. Pinocytosis is the engulfing of liquids of smaller substances.

27. Explain what is happening in the diagram through the process of exocytosis. Exocytosis is the process where a vesicle carrying a substance, fuses with the membrane, thus releasing the contents outside of the cell.

28. A cell is soaking in a 20% salt solution 28. A cell is soaking in a 20% salt solution. What percent of this solution is water? _____ If the cell itself has 10% solutes, what percent of the cell is water? ______. This makes the cell (hypo-, iso-, hyper-) tonic compared to the salt solution, which is (hypo-, iso-, hyper-) tonic. Water will therefore move ________ of the cell, and the cell will _____________ in size. 80% 90% out shrivel 20% salt = 80% water Hypertonic = more salt 10% salt = 90% water Hypotonic = less salt