1. What does tonicity refer to? Explain the movement of water if a cell were placed in a…
Tonicity is the ability of a solution to cause a cell to gain or lose water.
Hypertonic – water moves out of cell (cell shrivels)
Hypotonic – water moves into cell (cell swells, could lyse)
Isotonic – no net movement of water. (cell remains the same)
2. What type of solutions do plant & animal cells prefer?
Animals cells – isotonic solutions, Plant cells – hypotonic solutions
3. If an animal cell swells too much, it will what? What prevents a plant cell from doing this?
Animal cells will lyse (burst). The cell wall prevents plant cells from rupturing.
4. When a plant cell is in a hypotonic solution, it is not flaccid, but _____________.
turgid
5. List 2 differences between active & passive transport, and provide 3 examples of each.
Active – requires energy. Particles travel from low concentrated areas to high concentrated
areas. (sodium-potassium pump, endocytosis, & exocytosis)
Passive – No energy needed. Particles travel from areas of high concentration to areas of low
concentration. (osmosis, diffusion, facilitated diffusion)
6. What is “concentration gradient” and what is going “down or with” it and going “against it”?
The movement of particles. (down/with means from high to low) (against means low to high)
7. Endocytosis is a type of active transport. Give three examples of endocytosis, and explain
each.
Phagocytosis – cellular eating. Cell engulfs particles with pseudopodia.
Pinocytosis – cellular drinking. Cells gulps droplets of fluid.
Receptor – mediated endocytosis – receptor proteins bind specific molecules, & cell membrane
pinches inward to form vesicle.
8. Provide 2 examples of how a cell uses phagocytosis.
Organisms like amoeba take in food vacuoles. White blood cell (macrophage) engulfs bacteria.
9. List 5 functions of proteins found in the cell membrane.
Enzymes (chain reactions), transport, receptors, id tags, junctions.
10. How is active transport like facilitated diffusion?
They both use transport proteins. (although active transport requires energy)
11. How is facilitated diffusion different from diffusion?
facilitated diffusion uses a transport protein, but diffusion does not.
12. What is signal transduction?
Message transfer process, a messenger molecule binds to the receptor protein, which relays
the message to molecules within the cell.
13. What is hypercholesterolemia?
Disease, LDL receptors in receptor mediated endocytosis are defective, so they cannot take up
the LDLs. This cholesterol accumulates in the blood. Leads to atherosclerosis.
14. What are the 5 components that make up ATP?
Adenine + Ribose + Phosphate group + Phosphate group + Phosphate group.
15. Once ATP undergoes hydrolysis, what is the remaining molecule called?
ADP adenosine diphosphate.
16. What is it called when ATP gives a phosphate group to another molecule, such as a
transport protein?
Phosphorylation.
17. Name an example of a endergonic reaction & an exergonic reaction.
endergonic - photosynthesis
CO2 + H2O --add sunlight energy --> glucose molecule
(Low energy)
(high potential energy)
exergonic - cellular respiration
glucose molecule + O2 --release energy (ATP)--> CO2 + H2O
(high potential energy)
* Hydrolysis of ATP is also an exergonic reaction. A phosphate group is separated from an ATP
molecules releasing the energy stored in the bond, the remaining ATP molecule is now ADP.
18. What are the 3 types of energy that we talked about in class, and what is an example of
each?
Kinetic energy - energy of motion. ex: movement of transport proteins, or muscle proteins.
Potential energy - stored energy. ex: a glucose molecule has a lot of stored energy.
Chemical energy - potential in reactants is energy released in a reaction. ex: cellular respiration.
19. How much energy is unusable when converting glucose to ATP?
about 60% of the available energy is released as heat (disordered unusable energy).
20. What form does this unusable energy usually take, and why can’t organisms use it?
It is in the form of heat, and it is unusable because it is disordered.
21. What are the 2 laws of thermodynamics?
1st - (energy conservation) energy can neither be created nor destroyed, only transferred or
transformed into another type of energy (ex: burning wood releases the energy in the cellulose
(carbohydrate wood is composed of) in the form of heat & light).
2nd - during every energy transfer or transformation some energy becomes unusable (most
often in the form of heat which is disordered).
22. The increase in entropy means that there is an increase in what?
disorder
23. When you use energy from exergonic reactions to fuel endergonic reactions, this is called
what?
energy coupling
24. What is the difference between metabolism & metabolic pathway?
Metabolism refers to the TOTAL of an organisms chemical reactions (exergonic + endergonic)
Metabolic pathway refers to a single chain of events, a series of chemical reactions that result
in the building or breaking down of a complex molecule.
25. Why are the bonds between phosphate groups in ATP so easily broken?
Because all of the phosphate groups have a negative charge, which causing a mutual repulsion.
Thus the bonds between them are easily broken (by hydrolysis).
26. What does the “fluid mosaic model” explain?
"fluid" - molecules drift about because of the kinks in the fatty acid tails of the phospholipids (a
double bond in the tail is what causes the kink) prevents the phospholipids from packing tightly
together. (fluid as salad oil!)
"mosaic" - the membrane is made of many small pieces.
27.How does the ECM and the cytoskeleton communicate?
Integrin proteins relays messages between the ECM and the cytoskeleton.
28. If a carbohydrate is attached to a protein it is called a glycoprotein. What is it called if a
carbohydrate is attached to a lipid?
glycolipid
29. Why are glycoproteins important to the immune system?
For antibodies to fight foreign bodies such as bacteria, they must first be able to identify the
opposing cell. Glycoprotiens act as identification tags on cells so that they may be recognized by
other cells.
30. Do transport proteins have a shape that fits a specific solute? Do receptor proteins have a
shape that fits a specific messenger? Do receptors used in receptor mediated endocytosis pick
up specific molecules?
yes to all.
31. What does selective permeability mean?
Some substances are able to cross the membrane more easily than others.
32. How does a glucose molecule cross the cell membrane? How about ions?
Both cross with the assistance of transport proteins.
33. Why were phospholipids so critical in the formation of the first cells?
Because they are able to spontaneously self-assemble into simple membranes, providing a
"container" for cells.
34. If solution A has a higher concentration of solute than solution B, which direction will the
water flow during osmosis?
From solution B to solution A
35. List the 4 steps of active transport.
1. solute binds to transport protein at active site.
2. ATP transports a phosphate group to the transport protein (process called phosphorilation).
3. Energy release from phosphorilation causes transport protein to change shape, and release
solute on other side of membrane.
4. the phosphate group detaches from the transport protein which returns to its original shape.
Be sure to be able to identify and explain
the functions of all of the components of
the cell membrane. Use diagram to the
right.