Final answer:
The sarcomere of striated muscle extends from one Z line to another and forms the basic functional unit for muscle contraction in skeletal muscle fibers.
Step-by-step explanation:
The sarcomere, or contractile unit of striated muscle, extends from one Z line to another. The sarcomere is a fundamental functional unit of a skeletal muscle fiber involved in muscle contraction. It comprises repeating units within a myofibril and is delimited by structures called Z-discs (or Z-lines). Skeletal muscle tissue exhibits a striated appearance due to the alternation of dark (A) and light (I) bands organized in sarcomeres. Each sarcomere contains an entire A band and two halves of an I band, one on each side of the A band. The orderly pattern of sarcomeres contributes to the striation pattern characteristic of skeletal muscle fibers. These contractile units are equipped with actin and myosin protein filaments which slide past each other, causing the sarcomere, and consequently the muscle cell, to shorten and generate movement.