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.
Answer:
C ( sucrose converts to glucose and fructose )
Explanation:
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Explanation:
<u>F. Ribosome</u>
Around the endoplasmic reticulum, proteins are transported. The Endoplasmic Reticulum is a cytoplasmic membrane network. This continuous method not only raises the surface area within the cell but also conducts protein folding, synthesis, and transport.
Further Explanation:
Free ribosomes synthesize most proteins that operate in the cytosol (such as actin) or nucleus (such as DNA polymerase). Proteins that act within the endomembrane system (such as lysosomal enzymes) or those that are intended for cell secretion (such as insulin) are synthesized in the rough endoplasmic reticulum ER by bonded ribosomEs.
The rest of the ER that doesn't include ribosomes is called the smooth ER, and may contain lipids, enzymes, and other proteins. The first amino acids in the that polypeptide chain serve as a signal sequence as a protein bound for the endomembrane system is being synthesized by a ribosome. The signal sequence ensures that the ribosome binds to the ER's outer membrane and the protein gets into the ER lumen.
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Oxygen breakdown the food and release energy molecules as ATP
