AP BIOLOGY

Detailed explanation-1: -Recombinant insulin is synthesized by inserting the human insulin gene into E. coli, or yeast (Saccharomyces cerevisiae) which then produces insulin for human use.

Detailed explanation-2: -In 1978, rDNA technology was used for insulin synthesis using Escherichia coli.

Detailed explanation-3: -It was remarkable that these genes functioned in E. coli. Human insulin, which is comprised of a total of 51 amino acids (21 aa A chain and 30 aa B chain), was the first therapeutically useful protein product resulting from recombinant DNA technology.

Detailed explanation-4: -Among prokaryotes, Escherichia coli has always been preferred for production of recombinant proteins as it offered several advantages including high growth rate, simple media requirement, easy to handle, high yield and very cost effective.

Detailed explanation-5: -Genetically engineered insulin or humulin can be produced by inserting the human gene of insulin into a plasmid isolated from E. coli bacterium and then production of a number of copies or clones of that recombinant gene by insertion of the recombinant gene into another E. coli bacterium.