What is a restriction enzyme?
Q: What is a restriction enzyme?
A: A restriction enzyme is an enzyme that cuts DNA at specific locations or recognition nucleotide sequences called "restriction sites."
Q: What do all restriction enzymes do to cut DNA?
A: All restriction enzymes make two incisions, once through each strand of the DNA double helix.
Q: Where are restriction enzymes found?
A: Restriction enzymes are found in bacteria and archaea.
Q: What is the purpose of restriction enzymes in bacteria?
A: The purpose of restriction enzymes in bacteria is to defend against invading viruses called bacteriophages by selectively cutting up their foreign DNA.
Q: How does the host DNA protect itself during the restriction process?
A: The host DNA is protected by another enzyme that blocks cleavage and protects the host DNA against restriction.
Q: What are the restriction modification systems?
A: The restriction modification system describes the two processes of restriction and protection by enzymes, which work together to protect the host DNA and restrict foreign DNA in a process found in some prokaryotes.
Q: What is the importance of restriction enzymes in molecular cloning?
A: Restriction enzymes are vital tools in molecular cloning and are routinely used in laboratories for DNA modification. More than 600 commercially available restriction enzymes have been studied in detail, and over 3000 in total.
