Tutor profile: Alissa S.
Who defined institution by saying "institution is definite organization pursuing some specific interest in a specific way"?
Subject: US History
How many people were killed during the Salem with trials and what ended them?
Twenty people were executed and five more died in jail. The trials ended when the colony's governor called for the because his wife was accused of witchcraft.
Describe the process of a muscle contraction.
The first step to a muscle contraction is depolarization and calcium ion release. This is when an action potential triggers the release of acetylcholine into the motor end plate. This initiates depolarization. Depolarization causes the sarcoplasmic reticulum to release stores of Ca2+. Next, the actin and myosin cross bridge formation happens. The binding sites for the myosin are covered by troponin and tropomyosin (a blocking complex). Calcium ions bind to the troponin and change the complex, exposing the binding sites. The myosin heads then form a cross bridge with the actin filaments. The sliding mechanism is next. ATP binds to the myosin head destroying the cross bridge. ATP hydrolysis makes the myosin heads change position, pushing them toward the next actin site. Then the myosin heads bind to a new actin site. This drags the actin along the myosin in a sliding movement.
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