Question

In skeletal muscle, Z-line is connected to
A. Actin
B. Myosin
C. Tropomyosin
D. Hensen’s line

Answer 1

Hint: The skeletal muscle is considered to be the framework of bones that help in the movement of the body. Bones and cartilages are the two main parts of the skeletal muscle as connective tissues.

Complete answer:
Z-line is defined to be the lateral boundaries of a sarcomere. In muscles, Z-lines are found as a series of dark lines. It is found in the centre of each I-band that bisects the I-band.
The portion of myofibril between two Z-lines is known to be the functional unit of contraction. M-line is the thin filament which holds together the thick filament of A-bands.
A) Actin band is also known as an isotropic band. I-band is the light band and Z-line is present at the centre of each I band. So, it can be said that the Z-line is connected to Isotropic band or I band.
Considering other options-
B) Myosin is also known as anisotropic band or A-band. They are dark bands considered to be a thicker filament than actin. M-line connects the thick filament in A-band together at the middle of this band.
C) Tropomyosin is a protein present in the thin filament which runs close to the F-actins throughout its whole length. Troponin is distributed at regular intervals on the tropomyosin.
D) Hensen’s line is the H-line that joins the H-band. H-zone is the central part of thick filament which does not overlap with thin filaments.
So, option A is the correct answer.

Note: Sarcomere consists of the portion of two Z-lines. Z-line appears as a series of dark lines. It provides a connection between the contractile apparatus and the cytoskeleton. The M-line is present between the thick filament.