AP BIOLOGY

Detailed explanation-1: -EcoRI is a restriction enzyme or restriction endonuclease. It cuts the DNA double helix at a specific site. This restriction enzyme was first isolated from E. coli.

Detailed explanation-2: -EcoRI is isolated from E. coli strain RY13. I (Roman numeral) indicates it was the first enzyme of that type isolated from E.

Detailed explanation-3: -Eco RI is isolated from Escherichia coli RY13. Here ‘E’ shows the genus name Escherichia, ‘co’ shows the name of species coli and ‘R’ shows the strain of bacteria. The number ‘I’ shows that this was the first isolated enzyme from this strain.

Detailed explanation-4: -Restriction enzymes in the cell destroy not only invading phage DNA but also DNA transferred by conjugation, transformation or transduction. To protect incoming DNA, Escherichia coli strains lacking restriction systems, such as DH5 (r–K) and HB101 (r–B), are commonly used.

Detailed explanation-5: -Restriction Endonucleases For example, EcoRI, a restriction endonuclease isolated from Escherichia coli, cleaves DNA only at the sequence 5′-GAATTC-3′.