Question

In the sliding filament model of muscle contraction, I bands contain

A) thick filaments.
B) thin filaments.
C) myosin II.
D) myomesin.
E) both thick and thin filaments.

Answer 1

In the sliding filament model, I bands contain thin filaments, which interact with thick filaments to facilitate muscle contraction.

Step-by-step explanation:

In the sliding filament model of muscle contraction, I bands contain thin filaments. The I bands are the lighter regions on a myofibril and are flanked by Z discs. During contraction, the Z lines move closer together, making the I band smaller as the thin filaments slide inward. The answer to the question is B) thin filaments. The filament arrangement is crucial for the muscle contraction process, with the thin filaments pulling and sliding past the thick filaments due to the formation of cross-bridges between myosin on the thick filaments and actin on the thin filaments, facilitated by calcium ion entry into the sarcoplasm.