The DNA polymerase will know exactly where to begin replication. And just like this one, this one also contains the ampicillin resistance gene. So that means we can use this gene as a marker to basically differentiate between those sounds that did not take up the plasma and those cells that did. Now in addition, on top of these two things, this plasmid also contains a beta galactosidase gene. And that is a very important gene because what this gene does so remember, a plasmid not only can contain a gene that gives a resistance to antibiotics, but it can also contain a gene that produces special proteins needed to break down different types of molecules in that cell. And what this gene actually does is it produces a special enzyme that allows that cell to break down a particular type of sugar molecule for energy.