Download Key Unit 3 (Cell membrane)

Cell Membrane Study Guide
1.Describe the function of each of the following organelles:
Mitochondrion
Make ATP (energy)
Endoplasmic reticulum
Move proteins throughout the cell
Lysosomes
Break down waste and old cell parts
Central vacuole
Store water and wastes in plants
Chloroplasts
Photosynthesis
Cell wall
Surround cell membrane; provide structure and support
Golgi apparatus
Package and distribute proteins
Ribosomes
Make proteins
2. Smooth ER is lacking what organelle? Ribosomes
3. What is the difference between a channel protein and a transport protein? Channel
protein lets any molecule through it (like a bridge) whereas transport proteins are
specific to certain molecules (only let some things across)
4. Explain why a cell might swell if placed in some solutions.
Solution is hypotonic which means that there is lower concentration of solutes (so a higher
concentration of water) in the solution. This causes the water to travel into the
cell through osmosis causing the cell to swell.
5. If a cell is placed in salt water, water will leave the cell by what process?
Osmosis (solution is hypertonic)
6. Name the 2 most important characteristic of facilitated diffusion?
1) Facilitate means to “help” so this is diffusion with help. It is used for molecules that are
either charged or too big to fit across the cell membrane. 2) It requires no energy
because it is a flow of molecules downhill (from a high concentration to a low)
7. The net movement of particles from an area of high concentration to an area of low
concentration is called what?
Diffusion
8. The concentration of a solution outside the cell is the same as inside the cell, thus
there is no net movement of molecules. This is known as a _isotonic____ solution.
9. In the cell membrane, where are the fatty acid tails of phospholipid molecules
located? Inside (away from the water)
10. How does water leave a cell when it is placed in salt water? osmosis
11. What ability of the cell membrane prevents the inside of the cell from being exactly
like the outside of a cell? “selectively permeable” / homeostasis
12. Sugar molecules can enter cells through what process?
(hint, it does not require energy, but it is not diffusion)
Facilitated diffusion
13. In cells, ATP temporarily stores what?
Energy
14. Why is it dangerous for humans to drink ocean water?
It is hypertonic so the water will leave your cells and cause you to dehydrate even
faster.
15. At what point will the process of diffusion stop? Equilibrium
16. The dispersal of ink in a beaker of water is an example of what? diffusion
17. Placing a plant into a hypertonic environment will cause what to happen to the cells?
(be sure to mention turgor pressure)
Shrivel; decrease turgor pressure
18. Molecules moving from a region of low concentration to a region of high
concentration is what type of transport? (active/passive)
active
19. Ridding the cell of material by discharging it from sacs at the cell surface is called
what?
exocytosis
20. List 3 examples of active transport?
Active transport with a transport protein; Endocytosis, Exocytosis
21. Molecules that are too large to be moved through the membrane can be transported
into the cell by what method?
Endocytosis
22. Draw and label a cell membrane using the following terms:
Phospholipid bilayer
Channel protein
Transport/Carrier protein
23. Explain the how the sodium-potassium pump operates. Is this active or passive
transport?
Active; Pumps sodium in and potassium out
24. What does it mean to state that cell membranes are selectively permeable?
They will let some stuff come in and out of the cell but not everything.