Genetic engineering can be used to 
produce chemicals and hormones that
the body requires. For an example 
we'll use insulin for a diabetic 
person. First remove a certain gene
from a human cell using a restriction 
enzyme, in this instance we'll "cut" 
out the gene for producing insulin. 
Second extract a plasmid from a bacterial
cell and again "cut" it with the 
restriction enzyme. Insert the gene into 
the plasmid by attaching both of the 
"sticky ends" of the gene onto the ends 
of the plasmid. Now re-insert the hybrid
plasmid into the bacteria cell, where it 
will replicate to make new DNA for the cell.
Many more daughter cells can be cultured 
and used to make insulin.

this is a prokaryote, it has one chromosome and no nucleus

this is a eukaryote with one nucleus

Medical Uses of Genetic Engineering Links