Why do scientists construct recombinant dna molecules?

Restriction enzymes are particularly useful because they create "sticky ends" on the segments of DNA. Like Velcro, these sticky ends allow the DNA to join easily with complementary segments. The gene of interest and the plasmids are both exposed to the same restriction enzyme. This creates many different molecules.

meteorologists would compare a new weather map with one 24 h old to see how fast a front is moving.

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.