Answer:
Step-by-step explanation:
Muscle cell contraction is facilitated by the movement of ions across the cell membrane, resulting in a small electrical current. The two types of ions involved in this process are sodium (Na+) and potassium (K+) ions.
The process of muscle cell contraction is facilitated by proteins called voltage-gated ion channels. These channels open and close in response to changes in the electrical potential across the cell membrane. When a muscle cell is stimulated, voltage-gated sodium channels open, allowing a rapid influx of sodium ions into the cell. This results in a depolarization of the cell membrane and triggers the release of another protein, called the sarcoplasmic reticulum, which releases calcium ions (Ca2+) into the cytoplasm.
Calcium ions then bind to another protein, called troponin, which is located on the actin filaments. This binding causes a conformational change in troponin that exposes the active site on the actin filament. Another protein, called myosin, can then bind to the active site on the actin filament, forming a cross-bridge. The energy generated by ATP hydrolysis causes the myosin head to pivot, pulling the actin filament toward the center of the sarcomere and causing contraction.
In summary, the molecules involved in muscle cell contraction include voltage-gated ion channels, sarcoplasmic reticulum, calcium ions, troponin, and myosin. These molecules work together to produce the movement of ions across the cell membrane and the resulting small electrical current that facilitates muscle cell contraction.