Answer:
1.An action potential is conducted deep into the muscle fiber by the T tubule.
3.The membranes of the sarcoplasmic reticulum become more permeable to calcium ions.
4.Calcium ions diffuse into the sarcoplasm around the myofibril.
2.Calcium ions bind to troponin.
5.The troponin-tropomyosin complex moves exposing active sites.
Explanation:
The arrival of a nerve impulse at synaptic end bulbs stimulates the release of acetylcholine into the synaptic cleft. The acetylcholine binds to its receptors located on the motor end-plate followed by the opening of ion channels to allow the small cations such as Na+ to enter the muscle fiber and make it positive.
The change in the membrane potential triggers the action potential that propagates along the sarcolemma into the T tubules. The action potential stimulates the release of calcium ions from the sarcoplasmic reticulum into the sarcoplasm.
The released calcium ions combine with troponin. Binding of calcium ions to troponin stimulates conformational change in troponin that makes the tropomyosin to shift away from the myosin-binding sites of actin.
The myosin heads join the free binding sites to form cross-bridges leading to contraction of muscle fiber.
The correct answer for the question that is being presented above is this one: "penicillium and yeast." <span>Penicillium is a genus of ascomycetous fungi of major importance in the natural environment as well as food and drug production.</span>
Answer: so the answer is D
Explanation:
In
general, hormones that bind to plasma membrane receptors cannot pass through
cell membranes.
<span>
Membrane
receptors or cell surface receptors are receptors that are located in the
membranes of cells and usually are integral membrane proteins. The
extracellular molecules like hormones, neurotransmitters, cytokines, growth
factors are ligands that induce changes (signal cascade) within the cell.</span>