Question

The functional unit of a muscle fibre is the

• A. sarcolemma
• B. sarcoplasmic reticulum
• C. sarcomere
• D. sarcoplasm

Answer 1

The correct option is C sarcomere

The plasma membrane of a muscle fibre i.e sarcolemma, has parallelly arranged filaments called myofibrils. Myofibrils contain alternate light and dark bands. The light bands contain actin and is called I-band or isotropic band whereas the dark bands contain myosin and is called A-band or anisotropic band. Each I band has an elastic fibre called Z line which bisects it and the filaments are attached to this Z line. The region between two successive Z lines is the functional unit of contraction and is called sarcomere.