1. Loss of troponin T from the thin filament will result in which of the following?
a. No crossbridge activity with increases in calcium
b. Continually active cross bridge cycling in the absence of calcium
c. Shorter thin filaments
d. Loss of tropomyosin
e. There is no effect on control of crossbridges
2. Blebbistatin is a newly identified small molecule inhibitor of myosin heavy chain. Scientists determined that it binds to the myosin-ADP-Pi complex with high affinity and inhibits ADP-Pi release. What step of cross bridge function is affected?
a. ATP binding to the myosin head
b. Myosin binding to actin
c. Release of bound myosin from actin
d. It causes rigor mortis
e. Cross bridge movement
3. A patient comes to the clinic and is found to have a mutation in the gene for nebulin. This mutation does not change the amount of nebulin but the mutated form is 25% shorter in length but it still binds to the Z line as normal length nebulin would. With what you know about nebulin in skeletal muscle, you would predict which of the following?
a. Sarcomeric structure will be in a total state of disarray
b. Change in the shape of the length-tension curve under stretch
c. Change in the force-frequency pattern
d. Change in the myofilament spacing as viewed in electron micrographs of muscle in cross section
e. Increased reliance on glycolysis for energy
4. Caffeine is a known agonist of the ryanodine receptor in muscle. If you put caffeine on a single muscle fiber you would expect which of the following?
a. Generation of an action potential
b. Changes in DHPR status along the t-tubule
c. Increased SERCA activity
d. Hypertrophy of the muscle fiber
5. Age associated declines in muscle function are well documented with loss of strength (defined by decreased maximal force) occurring prior to loss of muscle mass. The change in strength without change in mass can be explained by which of the following?
a. Decreased number of sarcomeres in series
b. Loss of the motor endplate in some fibers
c. Decreased number of sarcomeres in parallel
d. Decreased numbers of mitochondria