Question

Describe the structure of actin and myosin filaments.

(The Length Sarcomere is $2.5\mu m($.Actin rod $=1\mu m,)$ myosin$=1.5\mu m$ $1$Myosin filament & $1$ Actin filament is surrounded by $3$ Myosin filament.)

Answer 1

In the muscle cells, myosin and actin are the major components. The muscle cells are always elongated slender and spindle-shaped fibre like cells they are therefore also known as muscle fibres.

This poses a large number of myofibrils which are formed of actin and myosin. In the striated muscles, this shows a transverse striation in the form of regular alternate dark anisotropic bands and light isotropic bands. The anisotropic band contains thick myosin filaments and isotropic band contains thin actin filament.

I band is divided into two equal parts by a thin fibrous transverse zig-zag partition which is known as Z band.

The space between two filaments forms a sarcomere.