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NEET · Biology · STD 11 - 17. Locomotion and movement

The \(H\)-­zone in the skeletal muscle fibre is due to

  1. A the central gap between actin filaments extending through myosin filaments in the \(A\)-band
  2. B extension of myosin filaments in the central portion of the \(A\)-­band
  3. C the absence of myofibrils in the central portion of \(A\)-­band
  4. D the central gap between myosin filaments in the \(A\)-band.
Verified Solution

Answer & Solution

Correct Answer

(A) the central gap between actin filaments extending through myosin filaments in the \(A\)-band

Step-by-step Solution

Detailed explanation

(a) : Each muscle fibre has many parallelly 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.