Biology · Biotechnology: Principles and Processes · NEET
NCERT gives a clear rule. The first letter (E) is the first letter of the genus Escherichia. The next two letters (co) are from the species coli. So the first three letters 'Eco' tell you the bacterium. The next letter (R) comes from the strain name, here Escherichia coli RY13. The last part (I) is a Roman numeral for the order in which the enzyme was isolated from that strain (I = first, II = second).
No. This is the most common trap. The R is NOT for 'restriction'. NCERT says the R is derived from the name of the strain (RY13). Many students wrongly expand EcoRI as 'Escherichia coli Restriction I'. The correct reading is genus + species + strain + order number.
The Roman numeral shows the order of discovery of enzymes from the same organism strain. The first restriction enzyme isolated is I, the second is II, and so on (like HindII, HindIII from Haemophilus influenzae). It is a counting number, not a letter, so it stays the same for that strain.
The first three letters come from the scientific name (genus + species), which is always italicised (Escherichia coli). The strain letter and the Roman numeral are not part of the scientific name, so 'RI' stays upright (not italic). In exams the correct written form is EcoRI with 'Eco' italic.
Both come from Escherichia coli, so both start with 'Eco'. The difference is the last part: EcoRI is one enzyme, EcoRV is another isolated later. They also cut differently. EcoRI makes sticky ends, while EcoRV makes blunt ends. The naming only tells you the source, not the cut type.
The specific palindromic sequence which is recognized by EcoRI is
Try the real previous-year questions from this chapter — each with the answer and a full solution.
There is no word 'full form'. It is a code: E (Escherichia genus) + co (coli species) + R (strain RY13) + I (first enzyme isolated from that strain). Together it names the source bacterium and the discovery order.
EcoRI comes from Escherichia coli, strain RY13. This is stated directly in NCERT Class 12, Biotechnology: Principles and Processes.
EcoRI is a restriction endonuclease. It cuts DNA at a specific internal recognition site, not from the ends. Exonucleases remove nucleotides only from the ends of a DNA strand.
HindII and HindIII both come from Haemophilus influenzae (genus H, species in, plus strain d). The Roman numerals II and III show they were isolated in that order from the strain.
NEET often asks you to match an enzyme to its source organism or to spot the wrong expansion of the name. Knowing the genus + species + strain + Roman numeral rule lets you decode any enzyme name and avoid the 'R = restriction' trap.
