Question

Choose the letter from the figure that most appropriately corresponds to the structure.

(i) A-band

(ii) I-band

(iii) Sarcomere

(iv) H-zone

(v) Myosin

(vi) Actin, Troponin, Tropomyosin

(vii) Z-line

A) (i) - E, (ii) - D, (iii) - F, (iv) - G, (v) - B, (vi) -C, (vii)-A
B) (i) - E, (ii) - D, (iii) - C, (iv) - G, (v) - B, (vi) -A, (vii)-F
C) (i) - E, (ii) - D, (iii) - F, (iv) - G, (v) - C, (vi) -A, (vii)-B
D) (i) - E, (ii) - D, (iii) - F, (iv) - A, (v) - B, (vi) -C, (vii)-G

Answer 1

Hint:
The above diagram shows a sarcomere Or functional unit of a muscle cell. A pattern of alternating light and dark bands is formed from the thick and thin filaments of sarcomeres.

Complete step by step answer:
The light bands are called I bands (isotropic) as the thin region is lightly stained and contains only thin filaments i.e., the D part. The dark bands of the sarcomere are called A-bands (anisotropic) i.e. when stained look dark due to thick filament. 1 represents A band. Both thick and thin filaments constitute A-band. In the center of the A-band, there is an H-zone present that has thick filaments and no thin filaments. Proteins that hold the thick filament forms the M-line at the center of the H-zone so it is called midline as it is in the middle of the sarcomere. The sarcomere is represented by F. Actin is the component of thin filaments and myosin is the component of thick filaments. 4 is represented by G where only thick filaments are present. B represents myosin filament. Actin, troponin, and tropomyosin are represented by C . B represents myosin which is the thick part. C represents thin filament. The z line is represented by the A part in the diagram.

Option ‘A’ is correct

Note:
Bipolar thick filaments walk toward the plus end of two sets of thin filaments of opposite orientations, driven by dozens of independent myosin heads that are positioned to interact with thin filaments. During muscle contraction the, I-bands shortens.