The Nrui site recognizes the sequence TCG CGA
The EcoRV recognizes G/AATTC
4172 bps will be the size of DNA fragment after treating with EcoRV and 3385bps will be size of DNA after treating with Nrui enzymes.
Explanation:
pBR322 is a plasmid vector having 4363 base pairs and there are 2 antibiotic resistant sites on it.
The two antibiotic resistant sites are for ampicillin and tetracyclin.
The cleavage site of EcoRV and Nrui sites are present in the tetracyclin resistant Gene region.
The EcoRV recognizes G/AATTC and cuts on palindromic sequences CTTAA/G and creates an overhang of AATT
It cuts the pBR322 at the 185 th bp.
The Nrui site recognizes the sequence TCG CGA
It cuts pBR322 at the 972 bps.
When pBR322 is treated with these two enzymes it will produce
4363 bp- 185-6 = 4172
4363- 972 bps-6= 3385
The insulin A gene chain is 21 amino acid long which means it has 63 base pairs. It will be inserted on cleavge with ecoRV or Nrui on tetracycline resitant gene of the vector.