Which of these processes need ATP most? O Detachment of myosin head O Release of calcium O None of these needs ATP O Release of acetylcholine O Attachment of myosin head
Contraction of muscles is controlled by two important proteins, actin and myosin.
In muscle cells, the sarcoplasm (cytoplasm) is made up of contractile proteins, which are arranged in units known as myofibrils. Myofibrils run from end to end in muscle cells and are attached to cell membrane (sarcolemma) of muscle cells.
Each myofibril contains myosin, actin, troponin, and tropomyosin. The functional unit of a myofibril is known as a sarcomere. In a sarcomere, actin and myosin are arranged in such a way that they can slide over each other.
Myosin proteins make up the thick filaments of the sarcomere, while actin proteins make up the thin filaments.
Muscle contraction can be explained by the cross-bridge cycle. In this cycle, myosin binds to actin (forms a cross bridge with it). The head of the myosin is then bent, which allows myosin to crawl along the actin filaments, causing contraction.
For contraction to occur, an action potential must be released from a neuron into the neuromuscular junction (NMJ). This stimulates the release of neurotransmitters, which then trigger muscle contraction. Muscle contraction is an energy dependent process.
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