Name _____________________ Per _______ KEY
Muscle Biochemistry Review
Use your book, your projects, your muscle packet and/or your notes to answer the following questions. Please be specific and complete.
Explain fully how the sodium/potassium ATPpump works:
1. What ions (charged molecules) move where?
3 sodium pumped out of muscle cell and 2 potassium pumped it
2. How many move?
see above
3. What substance is necessary in order for the pump to function?
ATP
4. Is this passive or active transport and why?
Active because it requires energy
5. Thinking about muscle contraction, what is the main goal of the Na+/K+ ATP pump?
reset: send sodium back out and potassium back into muscle cell and make inside of muscle cell negatively charged again
6. Where does the ATP come from (what process)?
cellular respiration
7. What two substances are necessary for the process in question #6 to occur?
glucose and oxygen
8. How would apnea (not breathing) affect this process?
no oxygen à no cellular respiration
9. How would starvation affect this process?
no glucose à no cellular respiration
Sodium
10. Where is the sodium “supposed” to be located to start things off in order for a muscle contraction to occur?
In the synaptic cleft
11. How does sodium get into the muscle cell from the synaptic cleft?
through sodium channels opend by ACh
12. If acetylcholine (ACh) docked with chemically-gated sodium channels in the sarcolemma but there was no sodium in the synaptic cleft, what would happen?
no sodium leaking into muscle cell à cell remains negatively charged à no contraction
13. How do you think a patient would present (what would they look like) if they were hyponatremic (low on sodium)?
weak muscles (because not many muscle fibers able to contract
Calcium
14. What are two places where calcium (Ca2+) is normally found prior to a muscle contracting (to start things off)?
outside the synaptic knob, sequestered in sarcoplasmic reticulum
15. How did it get there?
calcium pumps
16. Did it get there by active or passive transport?
active
17. What is necessary for this process to occur (what substance needs to be present and available)?
ATP
18. Inside the muscle fiber, what triggers the release of calcium from where it
is stored?
sodium diffusing into the muscle cell à cell becomes positively charged à voltage gated calcium channels in SR open
19. What do you think would happen if calcium was never released?
muscle fiber would not contract
Muscle contraction
20. Once calcium is released from its container in the muscle fiber, what does it bind with in order to start the muscle fiber contracting?
troponin
21. What protein moves over, exposing binding sites?
tropomyosin
22. If the Z-lines of a muscle fiber are getting closer together then the muscle cell is
a. Relaxing
b. Contracting
c. Not doing anything
d. Can’t tell
Muscle relaxation
23. Where does the calcium need to go in order for a muscle to relax?
back into the sarcoplasmic reticulum
24. Where does the sodium need to go during muscle relaxation?
back out into the synaptic cleft
25. Where does potassium need to go during muscle relaxation?
back into the muscle fiber
26. Are these processes active or passive transport and why?
active because they are pumped and pumps require ATP
27. What substance is necessary in order for the myosin heads to release from actin and be cocked back?
ATP
28. What is the chemical process that produces this substance?
cellular respiration
29. What two reactants must be present in order for this chemical reaction to occur?
glucose + oxygen
Miscellaneous
30. Which substance is produced, packaged in the neuron, diffuses across the synaptic cleft and is recycled for use back into the neuron?
acetylcholine (ACh)
31. Which of the following is true?
a. The A band contains only actin
b. The light band contains only myosin
c. The dark band contains the Z line
d. The dark band contains actin and myosin
32. What is the first source of energy during the first 10 sec of contraction?
ATP
33. What is the second source of energy during the first 10 sec of contraction?
creatine phosphate
34. After a minute, ______ is the next source of energy during muscle contraction
glucose
35. What are some side-effects of taking too much creatine?
a) muscle cells swell and could rupture (water rushes in by osmosis)
b) ruptured muscle cells release proteins (like actin, myosin, troponin, tropomyosin, AChE, channels and pumps) into the bloodstream. This is called rhabdomyolysis
c) rhabdo can lead to kidney (renal) failure
d) since water is tied-up in the muscle fibers, there is less available to sweat-out. Therefore there is a risk of hyperthermia and heat injury.
36. What step(s) of cellular respiration are aerobic?
Kreb’s cycle (Citric acid cycle) and the electron transport chain (ETC)
37. Which step(s) of cellular respiration is anaerobic?
glycolysis
38. What is the total number of ATP produced as a result of aerobic cellular respiration?
38 ATP
39. When oxygen is not present, _________ builds-up.
lactic acid
40. Oxygen is necessary to repay oxygen debt. Name three processes that oxygen is required for.
a) replenish used-up ATP stores
b) replenish used-up creatine phosphate stores
c) convert lactic acid back to glucose in the liver
muscle biochemistry review 5/3/2012 5