Sarcomere is distance between A. Two I-bands B. A and I bands C. Two Z-lines D. Z and A bands
Option C Each myofibril(a unit of the muscle cell) has alternate dark and light bands on it. The light bands contain actin and are called I-band or Isotropic band, whereas the dark band called ‘A’ or Anisotropic band contains myosin. In the center of each ‘I’ band is an elastic fibre called ‘Z’ line which bisects it. The thin filaments are firmly attached to the ‘Z’ line. The ‘A’ and ‘I’ bands are arranged alternately throughout the length of the myofibrils. The sarcomere is considered as the functional unit of contraction. The portion of the myofibril between two successive ‘Z’ lines is considered as a sarcomere. Hence sarcomere is the distance between two Z lines. So, the correct answer is 'Two Z-lines'.
