Which is the role of restriction enzymes? to isolate the selected gene
to cut DNA into fragments of different lengths
to move and separate the strands of DNA
to join the sticky ends of DNA fragments

The gene that causes sickle-cell disease is present in a higher percentage of residents of sub-saharan africa than among those of african descent living in the united states. even though this gene causes sickle-cell disease, it also provides some protection from malaria, a serious disease that is widespread in sub-saharan africa but absent in the united states. discuss an evolutionary process that could account for the different percentages of the sickle-cell gene among residents of the two regions.

Enzymes are proteins that speed up reactions by providing an additional energy source supplying additional molecules for the reaction removing inhibitors that slow down reactions lowering the amount of energy required

Why are fossils not found in igneous rocks? igneous rocks are made from cooling of lava or magma. igneous rocks are found too deep underground. igneous rocks are too dark in color to contain fossils. igneous rocks are too dense to contain fossils.