Armed with cutting and pasting enzymes, researchers can create new DNA molecules by "recombining" different fragments. In the 1970s, researchers first inserted a foreign DNA fragment into a loop of bacterial DNA, called a plasmid. This type of recombinant DNA can be transferred or stored for further study. The plasmid DNA (in red) must first be cut using a protein called a restriction enzyme. This particular enzyme (in blue), EcoR1, cuts DNA at a specific sequence: G A A T T C. When it finds the DNA sequence, the enzyme breaks the sugar-phosphate DNA backbone, leaving overhanging ends called "sticky ends." If a piece of foreign DNA (in pink) has been cut with complementary sticky ends, the ends will match together long enough to be pasted together by another enzyme called DNA ligase (in green). The "recombinant" plasmid, with its new gene insert, can now be transferred to another organism. (DNAi Location: Manipulation > Techniques > Cutting and pasting > Recombining DNA)

Loops of bacterial DNA, called plasmids, can be used to transfer fragments of foreign DNA — usually genes — into other organisms. The plasmid DNA (in red) must first be cut using a protein called a restriction enzyme. This particular enzyme (in blue), EcoR1, cuts DNA at a specific sequence: G A A T T C. When it finds the DNA sequence, the enzyme breaks the sugar-phosphate DNA backbone, leaving overhanging ends called "sticky ends." If a piece of foreign DNA (in pink) has been cut with complementary sticky ends, the ends will match together long enough to be pasted together by another enzyme called DNA ligase (in green). The "recombinant" plasmid, with its new gene insert, can now be transferred to another organism.

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