‘EcoRI’ has played very significant role in r-DNA technology.

Question

(i) ‘EcoRI’ has played very significant role in r-DNA technology.

(I) Explain the convention for naming EcoRI.

(II) Write the recognition site and the cleavage sites of this restriction endonuclease. 

(ii) What are the protruding and hanging stretches of DNA produced by these restriction enzymes called? Describe their role in formation of r-DNA.

Answer 1

(i) (I) The convention for naming EcoRI is as follows.

E – Escherichia

co – coli

R – Derived from the name of strain

I – Order in which the enzyme was isolated from that strain of bacteria.

EcoRI comes from Escherichia coli RY13

(II) EcoRI cuts the DNA between bases G and A only when the sequence GAATTC is present in the DNA.

(ii) The protruding and hanging stretches of DNA produced by restriction enzymes are called sticky ends. These are named so because they form hydrogen bonds with their complementary cut counterparts. This stickiness of the ends facilitates the action of the enzyme DNA ligase.