Using high-resolution microscopy ... Then the sarcomere shortens and the muscle contracts. In the absence of calcium, this binding does not occur, so the presence of free calcium is an important ...

Upon binding calcium, troponin moves tropomyosin away from the myosin-binding sites on actin (bottom), effectively unblocking it. Modified from Lehman et al. (1994).

PRESENTER:'Bones are made of calcium and other ... Often, our muscles work in pairs to move our bodies. In our leg, if the muscle on the back of our thigh contracts and gets shorter, it bends ...