This set of Molecular Endocrinology Multiple Choice Questions & Answers (MCQs) focuses on “Creatine and Creatine Kinase”.
1. Cytosolic isozyme is present in high ATP using regions in animal tissues.
a) True
b) False
View Answer
Explanation: A cytosolic isozyme is present in regions with high ATP use. By converting the generated ADP back to ATP during high ATP use, cCK (cytosolic creatine kinase) prevents ADP from accumulating in high concentrations that could inhibit ATP-using enzymes by mass action.
2. Where can we identify the presence of isozyme in mitochondria?
a) Porins present in the outer membrane
b) Intermembrane space
c) Cristae of inner membrane
d) Matrix, space within the inner membrane
View Answer
Explanation: The mitochondrial creatine kinase isozyme is found in regions where mitochondrial inner and outer membranes come into contact. This mitochondrial isozyme (mCK) is used to transfer the mitochondrial-generated ATP equivalents to the cytosolic sites of ATP use.
3. What compensates the lack of mitochondrial isozyme in a knockout mouse?
a) Osteocyte
b) Erythrocyte
c) Myocyte
d) Melanocyte
View Answer
Explanation: Myocytes compensate the lack of mitochondrial isozyme by developing more mitochondria in knockout mice. It is closely aligned with myofibrils and sarcoplasmic reticulum, facilitating accelerated migration of mitochondrial ATP to the sites of ATP use.
4. Which species diffuses to sites of ATP use in cytosol from the mitochondrion?
a) Creatine kinase
b) Creatine monohydrate
c) Creatine phosphokinase
d) Creatine phosphate
View Answer
Explanation: Mitochondrial creatine kinase (mCK) transfers a phosphoryl group from ATP to creatine (Cr) to form creatine phosphate (PCr), which diffuses to sites of ATP use. Cytosolic creatine kinase transfers the phosphoryl group into ATP at these sites. Cytosolic CK can also use glycolysis-produced ATP to synthesize PCr.
5. What is the concentration of PCr (Creatine Phosphate) in a resting muscle?
a) Three to five times that of ATP
b) Three to four times that of ATP
c) Two to six times that of ATP
d) Six to ten times that of ATP
View Answer
Explanation: The PCr concentration in the resting muscle is three to five times that of ATP. The reservoirs of ATP and PCr are replenished during cycles of low ATP demand in preparation for the next cycle with high demand for ATP.
6. What is the product that results from the spontaneous breakdown of creatine and phosphocreatine in the human body?
a) Creatine kinase
b) Creatinine
c) Creatine phosphokinase
d) Creatine monohydrate
View Answer
Explanation: Creatinine is a waste product formed by creatine and phosphocreatine breakdown and may also serve as an indication of renal activity. Creatinine is absorbed by the kidneys from the liver, filtering almost all of it from the blood and releasing it into the urine.
7. What is the main source of creatine in vegans?
a) Lysine, isoleucine and valine
b) Tryptophan, serine and cysteine
c) Glycine, arginine and methionine
d) Glycine, valine and methionine
View Answer
Explanation: De novo synthesis of glycine, arginine and methionine, which occurs mainly in the liver and kidney, will sustain elevated creatine levels in the body. De novo creatine synthesis is a major consumer of these amino acids, especially in vegans, where it is the only source of creatine. Creatine is not present in plants.
8. Which is the unique isozyme present in the heart?
a) CK-LDH
b) CK-CB
c) CK-DP
d) CK-MB
View Answer
Explanation: The heart muscle contains a special isozyme CK-MB (creatine kinase MB) that is not naturally present in the blood but it is produced when released from the heart muscle weakened by heart attack. Within two hours after the heart attack, the blood level of MB starts to increase. It generally increases 12 to 36 hours after the heart attack and returns to normal levels in 3 to 5 days.
9. What is the normal range of creatinine in the blood?
a) 0.8 to 1.4 mg/dL
b) 0.1 to 0.4 mg/dL
c) 0.4 to 1.0 mg/dL
d) 1.4 to 2.0 mg/dL
View Answer
Explanation: Creatinine levels in the blood are usually between 0.8 and 1.4 mg/dL. In diabetes and other disorders where renal activity is temporarily or permanently damaged, elevated blood creatinine indicates kidney failure.
10. What is the minimum requirement of creatine in body builders who are adding muscle mass?
a) 10g per day
b) 20g per day
c) 30 g per day
d) 8g per day
View Answer
Explanation: Body builders who add muscle mass have a stronger need for creatine and typically take creatine for a few days up to 20g per day, supplemented by smaller doses of maintenance. In high intensity short term practice, the combination of workouts and creatine supplementation improves muscle mass and improves efficiency.
Sanfoundry Global Education & Learning Series – Molecular Endocrinology.
To practice all areas of Molecular Endocrinology, here is complete set of 1000+ Multiple Choice Questions and Answers.
