Drag each tile to the correct box. Arrange the steps in the correct order to explain how a muscle fiber contracts.
Myosin and actin protein
filaments attach to each
other.
Calcium ions release into
the myofibrils.
Myosin filaments pull on
the actin filaments.
The nerve impulse reaches
the neuromuscular
junction.
The motor neuron carries
the nerve impulse.
The sarcomere shortens.

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before it leaves the nucleus of a eukaryotic cell, mrna is altered in the following ways: - a cap is added to the 5' end of the mrna molecule; - a poly a tail is added to the 3' end; - introns are removed and exons are spliced together.

answer:

convection currents in the magma drive plate tectonics. heat generated from the radioactive decay of elements deep in the interior of the earth creates magma (molten rock) in the aesthenosphere. the aesthenosphere (70 ~ 250 km) is part of the mantle, the middle sphere of the earth that extends to 2900 km.