Question

In describing a contracted sarcomere vs. a relaxed sarcomere, the contracted lacks which structures/components, while they are present in the relaxed sarcomere.

Where 1. A-band 2. I-band 3. Z discs 4. H-zone 5. M-line

A. 1 & 2
B. 3 & 4
C. 3, 4 & 5
D) 1 & 4
E) 2 & 4

Answer 1

The correct answer will be option E- 2 & 4.

Step-by-step explanation:

The sarcomere is a segment made up of thick and thin filaments between the two Z-lines or disc of a myofibril.

Sarcomere structurally can be divided into bands:

1. A-band- which is also known as the anisotropic filament is made up of thick filaments called myosin.
2. H-zone- the zone in the A-band which appears lighter in color in the microscope
3. I-band- an isotropic band made of thin filament called actin.

Upon contraction of muscle, these filaments form an overlapped structure due to which I-band shortens along with H-zone of A- band. Due to the shortening of these bands, only A-band without H-zone and I-band appears between two A-lines. These bands upon relaxation again take their normal form.

Thus, option E- 2 & 4 is the correct answer.