Answer:
The answer is C.
Explanation:
The submentovertex or the full basal projection of the skull is used best to demonstrate the base of the skull or the base of cranium. In this method, the x-rays' direction is starting from under the chin and exiting at the vertex or the top of the skull.
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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.
Diffusion is the movement of particles from a high concentration area to a low concentration area.
Things that can go through a membrane are ions (charged), small polar molecules. Big molecules can't go through the membrane due to its large size and disrupting the membrane.
Passive transport is the movement of substances acrpss the cell membrane w/o the use of energy. Active transport needs energy to move substances across a cell membrane.
Answer:
DNA is found in the nucleoid
