INTRODUCTION TO MICROSCOPY CELL BIOLOGY
CYTOSKELETON
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
calcium binds to troponin which moves the tropomyosin that otherwise blocks the interaction of actin and myosin.
|
|
|
calcium binds to tropomyosin which moves the troponin that otherwise blocks the interaction of actin and myosin
|
|
|
calcium binds to actin allowing it to associate with myosin.
|
|
|
calcium binds to myosin allowing it to associate with actin
|
Detailed explanation-1: -(2) Calcium binds to troponin C, which induces a conformational change in the troponin complex. This causes tropomyosin to move deeper into the actin groove, revealing the myosin-binding sites.
Detailed explanation-2: -(b) When the [Ca2+] rises, Ca2+ binds to a subunit of troponin, which causes the tropomyosin to shift slightly into the groove of the actin filament. The shift in position of tropomyosin allows the myosin heads to bind to actin. Lowering of the [Ca2+] level results in reversal of these events.
Detailed explanation-3: -Troponin and tropomyosin are two proteins that are present on the thin filaments of the muscle cells and help in the contraction of muscles. However, they have opposite functions. While troponin promotes muscle contraction, tropomyosin blocks muscle contraction.