LAB QUIZ__ BIO 201L_ALL QUESTIONS EXAMINABLE||ANSWERS CORRECT|| RATED 100%

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Lab. 7 pre lab questions. 1. How do banding patterns change when a muscle contracts? Provide the illustrations and reasoning for your answer. When a muscle contracts, the actin and myosin myofilaments... decrease in length which causes them to come together and the H zones and I zones shrink and become narrow. The A band doesn’t change during contraction. 2. What is tA muscle organ is a tissue that is made from cells and fibers and produces movement throughout the body causing contraction. A muscle fiber is a single muscle tissue cell and consists of more than one nucleus. It is composed of myofibrils that contract when they are stimulated. Myofibril is found in striated muscle cells and is made from actin and myosin. Myofilaments make up a myofibril.he difference between a muscle organ, a muscle fiber, myofibril and myofilaments? Provide the illustrations and reasoning for your answer. 3. Outline the molecular mechanism for skeletal muscle contraction. At what point is ATP is used and why? Provide the illustrations and reasoning for your answer. Molecular events take place between actin and myosin filaments. A myosin head binds to an actin filament and performs a power stroke and then releases. The myosin head must bind to a fresh molecule of ATP to disconnect. After myosin releases actin it hydrolyzes the ATP and initiates another cycle of actin/myosin interaction. ATP is a short-term energy booster and has large amounts of energy that is released when turned into ADP. 4. Explain why rigor mortis occurs. Provide the illustrations and reasoning for your answer. Rigor mortis is the stiffness of death and is only a temporary state that lasts for about 72 hours and happens about 4 hours after death. Every muscle in the body contracts and remains contracted during this period. This is happening because the circulation system has stopped and because muscles rely on phosphagen and require ATP. The lack of ATP disables myosin heads from detaching from actin. In the meantime, calcium ions leak from extracellular fluid and sarcoplasmic reticulum. They are now unable to recall these ions into the muscle fiber. The ions are still performing their tasks and disengaging tropomyosin and troponin from the active myosin sites. Muscle contract when the myosin shifts but because there is no ATP it can’t detach anymore and that’s why the muscle stays contracted. [Show More]

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