5. Explain why a plasmid and a segment of DNA to be inserted into a plasmid must be cut with the same restriction enzyme. Use the term sticky ends in your response.

Question

5.	Explain why a plasmid and a segment of DNA to be inserted into a plasmid must be cut with the same restriction enzyme. Use the term sticky ends in your response.

anonymous · Answer

Because the restriction enzymes will create a specific "sticky end" (overhanging nucleotides). As long as the insert and the plasmids are cut with the same restriction enzyme, they will fit together. If they would be cut with a different enzyme (at least enzymes that create different sticky ends), they would not fit together. 
I hope this helps you. $\LARGE\color{Black}{\ddot\smile}$