Final answer:
Bacteria, specifically E. coli, have been genetically engineered to produce human insulin using recombinant DNA technology since 1978. This method, known as 'humulin', produces insulin that is identical to human insulin and has improved treatments for diabetes patients. Recombinant DNA technology in microorganisms also enables vaccine production.
Step-by-step explanation:
The type of organism that has been successfully modified using genetic engineering to produce large quantities of human insulin is bacteria. Specifically, E. coli bacteria have been used since the late 1970s to manufacture human insulin through the process of recombinant DNA technology. This technology involves inserting the human insulin gene into bacterial cells, enabling them to produce insulin. This method of producing insulin, often called 'humulin', is chemically identical to the insulin produced naturally in the human body and has significantly reduced the occurrence of allergic reactions compared to when animal insulin was used for treatment.
Recombinant DNA technology is not only used for producing insulin but also for the engineering of microorganisms to create vaccines. The microorganisms are genetically modified to carry fragments of DNA that code for antigens. These antigens can stimulate an immune response without causing the disease, leading to vaccine production. Thus, genetically engineered microorganisms serve as factories for both therapeutic proteins like insulin and for the production of recombinant vaccines.