question_answer

Which of the following statements about the molecular arrangement of actin and myosin in myofibrils is incorrect?    

(i) Each actin (thin filament) is made of 2F (filamentous) actins.

(ii) F-actin is the polymer of G (globular) actin.

(iii) 2F-actins are twisted into a-helix.

(iv) Two strands of tropomyosin (protein) lie in the grooves of F-actin.

(v) Troponin molecules (complex proteins) are distributed at regular intervals on the tropomysin.

(vi) Troponin forms the head of the myosin molecule.

(vii) The myosin is a polymerised protein.

A) (i), (iii), (vii)                               

B) (ii), (iv) and (v)

C) Only (vi)                                   

D) Only (iii)