Question
Biology Question on locomotion and movement
H-zone in skeletal muscle fibre is due to
Extension of myosin filaments in central portion of A-band
Absence of myofibrils in central portion of A-band
Central gap between myosin filaments in A-band
Central gap between actin filaments extending through myosin filaments in A-band
Central gap between actin filaments extending through myosin filaments in A-band
Solution
Each muscle fibre has many parallely arranged myofibrils. Each myofibril contains many serially arranged units called sarcomere which are the functional units. Each sarcomere has a central ‘A’ band made of thick myosin filaments, and two half ‘I’ bands made of thin actin filaments on either side of it marked by ‘Z’ lines. In a resting state, the edges of thin filaments on either side of the thick filaments partially overlap the free ends of the thick filaments leaving the central part of the thick filaments. This central part of thick filament, not overlapped by thin filaments is called the ‘H’ zone.