For selection of recombinants, insertional inactivation of antibiotic marker has been superceded by insertional inactivation of a marker gene coding for a chromogenic substrate. Give reasons.
 

Agarose is extracted from

The presence of a chromogenic substrategives………… ……coloured colonies

In $pBR322$, codes for the proteins involved inthe replication of the plasmid.

Which of the following statement is not correct regarding Eco $RI$ restriction endonuclease enzyme?

$I.$ Eco. $RI$ restriction endonuclease enzyme is isolated from Escherichia coli $RY13$

$II.$ Its recognition sequence is $5^{\prime}-$ $GAATTC – 3 '$

$3^{\prime}-C T T A A G-5^{\prime}$

$5^{\prime}-G-A-A-T-T-C-3^{\prime}$

$3^{\prime}-C-T-T-A-A-G-5^{\prime}$

$III.$ Its site of cleavage is