Question

The commercially available pUC57 plasmid is circular with 2710 bp. It has one EcoRI cleavage site at 396 and one HindIII cleavage site at 471. How many bands would you expect to see on the gel if both enzymes were used to digest the enzyme and the digestion was complete? Explain your answer.

Using the same plasmid and restriction enzymes as in question 2, how many bands would you expect to see on the gel if the digestion were partial? A partial digestion means that

not every site on every molecule is cleaved by the restriction enzyme. Explain your answer

Answer 1

First Question:

As the plasmid is circular & it has two restriction sites (EcoRI & HindIII), after digesting the plasmid using both restriction enzyme if complete digestion occurs, we will observe two bands. This is due to the fact that we will get two fragments- one between 396 & 471 bp (Site A; 75 bp) & another between 471 & 396 bp (Site B; 2635 bp). This is shown in below picture.

Second Question:

When partial digestion occurs, we will expect to observe one band. This is due to the fact that in partial digestion only one of the restriction sites will cleave & other will not cleave. It will be resulted in the one band of 2710 bp (Total plasmid size).