The functional unit of a muscle cell is known as a "sarcomere" which covers the distance between the two Z-lines.
The sarcomere consists of A-zone which contains both thick and thin filaments, H-zone which contains only thick filaments and I band which contains only thin filaments.
During muscle contraction, thick and thin myofibrils slide over each other due to which the distance between two z-line get reduced.
The H and I zone gets shortened but A zone does not shorten but come close to other A- bands and disappears.
The process in which the genetic code carried by mRNA is translated into a sequence of amino acids. Occurs on ribosomes. Protein synthesis begins with DNA. The reason for this is simple: DNA contains the genetic information for everything in our bodies.
