Cross bridge is a structure that is globular made up of the actin filaments and activated myosin attachments. The head of the myosin binds to the binding site that is present on the actin filaments that are exposed to the actin molecules.
Due to this structure, the movement in muscle occurs as they contract while attaching temporarily to the actin filament that is present near and exposed.
d. the movement of myosin head while attached to actin myofilament
Explanation:
During muscle contraction, the calcium ions released from the sarcoplasmic reticulum in the sarcoplasm bind to troponin which in turn removes tropomyosin from the myosin-binding sites present on the actin. Hydrolysis of ATP at the myosin heads energize them. These myosin heads with stored energy bind to the myosin-binding sites on the actin filaments. In their bound conditions on the actin filaments, myosin heads are called cross bridges. Only one myosin head of a single myosin molecule forms cross-bridge at a time.
According to modern classification I will say that Jake is correct. With the use of tracing back and DNA technology then we can say that this is the digital way which is used nowadays to classify animals.
Sophie says through her observation that the characteristics of the animal classification used.
