163. What is the function of calsequestrin? a. To lower the free Ca2+ ion concen

Question

163.      What is the function of calsequestrin?

a. To lower the free Ca2+ ion concentration inside the lumen of the sarcoplasmic reticulum

b. To raise the free Ca2+ ion concentration inside the lumen of the sarcoplasmic reticulum

c. To make Ca2+ for release into the cytosol

d. To pump Ca2+ into the sarcoplasmic reticulum

PassagaektheatRStipasm162-169) For active muscle cells the delivery of oxygen to the ce far too slow to maintain sufficient energy levels, thus many muscle cells contain large amounts of myoglobin. which along The functional unit of a skeletal masclc cell i the sarcomere is with the cytochromes in the mitochondrial membrane impart a The protein polymers actin and myosin lie lengthwise along a red hue to the muscle sarcomere creating the various regions shown in Figure Band. 162. Which of the foilowing proteins is an ATPase? 2 line H Zone. actin myosin C. phosphocreatin D. calsequestrin 163. What is the function of calsequestrin to lower the free Ca on concentration inside the umen of the sarcoplasmic reticulum to raise the free Ca A Band nside the on concentration umen of the sarcoplasmic reticulum Sarcomere C. to make Caa for release into the cytosol to pump Ca nto the sarcoplasmic reticulum Figure 1 A sarcomere 164. Two types of skeletal muscle are named after their char A group of muscle cells within a muscle may be innervated c color, red muscle and white muscle. Which of by a single neuron making up a motor unit. The neuron camies acteris the following statements is most likely crue concerning o each muscle cel in the motor unit. The an action potential these muscle types? action potential is delivered deep into each muscle cell via ubular invaginations in the sarcolemma or cell membrane Both muscle types contain large amounts of myo called tubules. The change in membrane potential is trans globin and mitochondria ferred to the sarcoplasmic reticulum, which causes it to become White muscle contains more mitochondria than red permeable to Ca ons and to release its large siores of calcium muscle into the cytosol. Once in the cytosol, the Ca ons cause a C. White muscle is capable of onger periods of co nformational change in the prouein troponin, which in turn traction than red muscle acts upon a second proteiD, tropomyosin, exposing an actin D. Red mascle is capable of longer periods of contrac myosin binding site. Upon binding, the actin and myosin slide tion than white muscle past each other shortening the sarcomene and creating a muscu lar contraction. ATP then binds to myosin releasing it from 165. Which of the following concentrations changes the most actin. Myosin immediately hydrolyzes ATP using the energy to ithin the cytosol during the contraction of a muscle cell? retum to its read position. The Ca2 ions are removcd fron the cytosol by extremely efficient calcium pumps via active trans- A. ATP port. Once the Cai has been sequestered back into the lumen Myosin f the sarcoplasmic reticulum, the Ca ons are bound by Actin calsequestrin Although the direct source of energy for muscle contraction comes from ATP, the ATP concentration in actively contracting muscle remains virtually constant. In addition, it has been shown that inhibitors of glycolysis and cellular respiration have no effect oo ATP levels in actively contracting muscle over the short term. Instead, phosphocreatine donates its phosphate group to ADP in a reaction catalyzed by creatine kinase Phosphocreatine levels are replenished via ATP from glycoly sis and cellular respiration. 228 Copyright 2007 Examkrackers, Inc. GO ON TO THE NEXT PAGE.

Explanation / Answer

163. As per the passage, the role of calsequestrin is to lower the free Ca2+ ion concentration inside the lumen of the sarcoplasmic reticulum.

Each calsequestrin can bind upto 50 ca2+ ions. This helps the sarcoplasmic reticulum to store high amount of calcium ions in it.

So the answer is option A.

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.