Please choose the best option for each part. Part A. Which one of the following
ID: 3511330 • Letter: P
Question
Please choose the best option for each part.
Part A. Which one of the following statements concerning skeletal muscle and adipose tissue fatty acid metabolism is correct?
a. Fatty acids in the blood require both a fatty acid transporter to enter the muscle cell and a carnitine-based translocase to enter the mitochondria.
b. Hormone-sensitive lipase catalyzes the breakdown of triglycerides circulating in the bloodstream into fatty acids for uptake into muscle.
c. The percent contribution of skeletal muscle and adipose tissue to the overall body metabolic rate at rest is greater than their contributions to overall body mass.
d. Insulin activates adenylate cyclase and cAMP production, which in turn activates protein kinase A, and an increase in adipose tissue triglyceride lipolysis.
Part B. Which one of the following statements concerning skeletal muscle metabolism is incorrect?
a. Conditions that promote protein kinase activities increase glycogen breakdown, and conditions that promote protein phosphatase activity increase glycogen synthesis.
b. Glucose uptake from the blood, via the translocation of GLUT4 transporters to the
c. sarcolemma, is stimulated by epinephrine.
d. Liver glycogen breakdown during exercise produces glucose for release into the blood, but muscle glycogen breakdown does not.
e. Glycogen breakdown during contraction is stimulated by Ca2+, which activates phosphorylase kinase, and in turn phosphorylates and activates glycogen phosphorylase.
Part C. Which one of the following statements concerning the sarcoplasmic reticulum (SR) calcium release channel in malignant hyperthermia susceptible muscle is correct?
a. RYR1 mutations that cause muscle disorders are randomly scattered along the primary amino acid sequence.
b. RYR1 mutations that cause central core disease have a less deleterious effect on channel function than RYR1 mutations that only cause malignant hyperthermia susceptibility.
c. Isolated SR calcium channels from malignant hyperthermia susceptible individuals have an increased channel open probability at any activating Ca2+ concentration.
d. Isolated SR calcium channels from malignant hyperthermia susceptible individuals are always open, even at very low stimulatory Ca2+.
Explanation / Answer
A. Answer is option a
option a is perfect: Fatty acid in blood stream need a transporter protein to be transported into muscle cell cytoplasm and another carnitine based translocase to be transported into mitochondria
Option b: Hormone sensitive lipase is an intracellular enzyme located inside adipose tissue, so it hydrolyzes stored lipid inside adipose tissue not the lipid in circulating blood stream. Pancreatic lipase hydrolyzes the circulating triglycerides in blood not the hormone sensitive lipase.
Option c :It is clearly a false statement. Adipose tissue and muscle tissue has least contribution to body metabolism at rest. Adipose and muscle fat is the last option of body to use as energy source during starvation or heavy work.
option d: Insulin inhibits the process lipolysis & promote lipogenesis.
B. Answer is c.
Glucose is taken up by cells with the help of GLUT4. When there is increase in serum glucose, insulin is secreted and it binds to adipose tissue, muscle cell. On binding of insulin, intracellularly stored GLUT4 translocates to plasma membrane and facilitates glucose uptake by cell.
But epinephrine is a shock response protein. Epinephrine increse plasma conentration of glucose, so ephinephrine oppose the action of GLUT4 to keep glucose in plasma.
So the option c is incorrect, epinephrine oppose the availability GLUT4.
C. Answer is c
option 1: Mutation in RYR1 receptor is always in R1086 reisue. So its incorrect.
option 2 : Central core disease have same susceptibility to develop hyperthermia, so it is also incorrect.
Option 3(c) : Correct: the main pathology in Malignant hyperthermia is increased Ca2+ channel open probability at any concentration of Ca2+ , that is the main reason.
option d: is clearly incorrect.