Answer:
When a muscle cell contracts, the myosin heads each produce a single power stroke.
Explanation:
In rest, attraction strengths between myosin and actin filaments are inhibited by the tropomyosin. When the muscle fiber membrane depolarizes, the action potential caused by this depolarization enters the t-tubules depolarizing the inner portion of the muscle fiber. This activates calcium channels in the T tubules membrane and releases calcium into the sarcolemma. At this point, <em>tropomyosin is obstructing binding sites for myosin on the thin filament</em>. When calcium binds to the troponin C, the troponin T alters the tropomyosin by moving it and then unblocks the binding sites. Myosin heads bind to the uncovered actin-binding sites forming cross-bridges, and while doing it ATP is transformed into ADP and inorganic phosphate which is liberated. Myofilaments slide impulsed by chemical energy collected in myosin heads, <u>producing a power stroke</u>. The power stroke initiates when the myosin cross-bridge binds to actin. As they slide, ADP molecules are released. A new ATP links to myosin heads and breaks the bindings to the actin filament. Then ATP splits into ADP and phosphate, and the energy produced is accumulated in the myosin heads, which starts a new binding cycle to actin. Z-bands are then pulled toward each other, thus shortening the sarcomere and the I-band, and producing muscle fiber contraction.
<span>The astronaut then measures the abundance of magnesium on the new planet, obtaining the following results:
Isotope Abundance (%) Mass (amu)
24Mg 78.99 23.99
25Mg 10.00 24.99
26Mg 11.01 25.98
The atomic mass of magnesium for this planet = </span><span>24.31 amu</span>
Answer:
Due to sloppy nature of the field.
Explanation:
This problem of rapidly drainage can be solved if the field should leveled because the portion is rapidly drained due to sloppy nature of the field. Sloppy nature of land moves water at the faster rate from higher elevation to lower elevation. We can see in tillage practices, the farmers used levelers in order to level the field in order to provide even resources such as fertilizers and water. So we can say that this problem can be solved if the field will be leveled.
