Answer:
<em> A nick is created between G and A in GAATTC when using Eco R1 site while a nick is generated between G and G in GGATCC when Bam H1 is used. The difference in the nicks created is the main reason you observe two bands when you digest the circular plasmid with a mixture of both</em>
Explanation:
Circular plasmid containing : 9 kb of DNA
Eco R1 and Bam H1 are known as restriction sites in DNA ( i.e. special sequences found in a DNA ) hence they can be specifically cleaved by the restriction enzymes enabling the insertion of a gene. that is why you will get a same result when you digest the Plasmid with either Eco R1 or Bam H1
<em>but A nick is created between G and A in GAATTC when using Eco R1 site while a nick is generated between G and G in GGATCC when Bam H1 is used. The difference in the nicks created is the main reason you observe two bands when you digest the circular plasmid with a mixture of both</em>
