Hair and nails are part<span> of the integumentary </span>system<span>.</span>
Less expensive source of energy is available.
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The endoplasmic reticulum can either be smooth or rough, and in general its function is to produce proteins for the rest of the cell to function. The rough endoplasmic reticulum has on it ribosomes, which are small, round organelles whose function it is to make those proteins.