Recombinant DNA Technology (rDNA)

What is the very first step in the rDNA process before you can alter a bacterium?

Isolate the wanted gene (the specific DNA sequence you want to replicate, like the human insulin gene).

How do scientists prepare the bacterial plasmid to receive the new gene?

They cut out a specific part of the plasmid using restriction enzymes (molecular scissors) to create an opening.

What happens during the "replace" (or pasting) stage of rDNA?

The isolated wanted gene is inserted and glued into the cut plasmid (using an enzyme called DNA ligase) to create a recombinant plasmid.

Once the recombinant plasmid is created outside the cell, what must be done with it?

Put the plasmid back into the bacterium (a process called transformation).

How do scientists get a large amount of the desired gene or protein once the bacterium has the plasmid?

Replicate. They allow the modified bacterium to grow and divide rapidly, creating millions of identical clones.

Why is an "antibac plate" (antibiotic selection) used after trying to put the plasmid back into the bacteria?

To weed out the failures. The plasmid contains an antibiotic-resistance gene. When grown on an antibiotic plate, only the bacteria that successfully took in the plasmid will survive; the rest will die.

What is the purpose of adding a "chemical inducer" at the very end of the process?

It acts as an "ON switch." It triggers the surviving bacteria to start reading the inserted gene and mass-producing the actual protein (like insulin).

Can the plasmid-based rDNA process be used to directly edit a gene inside a living animal's chromosome?

No. Plasmids are great for using bacteria as factories to make proteins (like insulin or biofuels), but fixing genes inside a living organism’s native chromosomes requires newer tools like CRISPR.