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Hey, biology fans.
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Welcome to numerade today.
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We are looking at a myofibril, which is a subunit of a muscle cell.
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And specifically, we want to talk about four proteins that you find in the myofibril that are very important to the function of the muscle.
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And so the green protein here that is very thick represents a protein called myosin.
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So think of the myosin as the thick filaments in a myofibril.
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And then the red thinner filaments represent a protein called actin.
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And think of, again, think of actin as the thin filaments.
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Notice that the thin filaments, the actin proteins, are lie just above the myosin.
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Actually, they lie above and below.
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In this picture, they lie above the myosin proteins.
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They're not actually connected.
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And on the myosin, you see these little, these little look like little ores or paddles.
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They're heads of the myosin filaments that need to, connect to the actin and need to form a cross bridge with the actin.
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The reason that they cannot form the cross bridge in a relaxed muscle is because of a couple of other proteins...