During muscle contraction, each Blank______ monomer has an open active site to bind with the protein myosin.Multiple choice question.troponintropomyosinG-actin

The correct answer to the question is G-actin.

Explanation:

1. Active Sites in Muscle Contraction: During muscle contraction, the interaction between actin and myosin is crucial. G-actin, or globular actin, is the form of actin that has an open active site to which the myosin head can bind.

2. Troponin and Tropomyosin: These proteins regulate the contraction process. Tropomyosin typically covers the binding sites on actin, while troponin helps to reposition tropomyosin in response to calcium ions, allowing for muscle contraction.

In summary, during muscle contraction, G-actin monomers are the ones with open active sites where myosin binds, facilitating the contraction process.