# How Scientists First Made DNA Replicate in New Cells > This 1980 patent describes a method for cutting and pasting DNA pieces in a lab to create new, self-replicating genetic material that can be inserted into bacteria, a foundational technique for genetic engineering. - **Patent:** US 4237224 - **Original title:** Process for producing biologically functional molecular chimeras - **Owner:** Leland Stanford Junior University - **Granted:** 1980 - **Status:** Public domain (expired) - **Times cited:** 346 - **Field:** biotech, pharmaceutical, semiconductors ## What it does This patent details a process for creating 'biologically functional DNA' outside of a living cell, then introducing it into a microorganism, like bacteria, so it can make copies of itself and potentially produce specific proteins. The method involves cutting a circular DNA molecule (like a plasmid or virus DNA) into a linear piece with specific ends, then attaching another piece of DNA that contains a desired gene. This combined DNA, called a 'replicon,' is designed to be able to replicate within a host cell. The patent specifically mentions creating 'transformants' – cells that have successfully incorporated this new DNA. A key part is using a gene for a 'phenotypical trait,' like resistance to a substance, to easily identify the modified cells from the original ones. For example, claim 4 describes using resistance to a growth-inhibiting substance to select for bacteria that have taken up the new DNA. ## What it does NOT cover - Does not cover methods where the DNA is not prepared 'in vitro' (in a lab). - Does not cover DNA segments that do not contain an intact 'replicon' (the part needed for self-replication). - Does not cover inserting DNA into organisms other than unicellular ones like bacteria. - Does not cover the use of DNA segments that cannot be 'ligated' or joined together by their ends. - Does not cover the production of proteins in organisms that naturally exchange genetic information with the source of the gene. ## The clever bit The innovation was in precisely cutting and joining different DNA fragments in a controlled, in-vitro manner to create a functional, self-replicating unit that could then be reliably introduced and selected for within a host organism. ## Real-world examples 1. Production of recombinant human insulin 2. Manufacturing of monoclonal antibodies 3. Development of genetically modified crops 4. Research using E. coli as a host organism 5. Enzyme production for industrial processes ## Why it matters This patent represents a cornerstone of modern biotechnology. It describes the fundamental technique of recombinant DNA technology, allowing scientists to insert specific genes into microorganisms. This capability paved the way for producing vital medicines like insulin and human growth hormone, developing genetically modified crops, and countless other applications in research and industry. ## Frequently asked questions ### What does How Scientists First Made DNA Replicate in New Cells cover? This 1980 patent describes a method for cutting and pasting DNA pieces in a lab to create new, self-replicating genetic material that can be inserted into bacteria, a foundational technique for genetic engineering. ### Who owns patent US 4237224? Leland Stanford Junior University owns this patent, granted in 1980. ### When does this patent expire? This patent has expired and is now in the public domain — anyone can use the invention freely. ### What is patent US 4237224 cited by? This patent has been cited by 346 later patents that build on its ideas. ### What problem does this patent solve? This patent represents a cornerstone of modern biotechnology. It describes the fundamental technique of recombinant DNA technology, allowing scientists to insert specific genes into microorganisms. This capability paved the way for producing vital medicines like insulin and human growth hormone, developing genetically modified crops, and countless other applications in research and industry. ### What does this patent NOT cover? Does not cover methods where the DNA is not prepared 'in vitro' (in a lab). **Full plain-English explainer:** https://patentbrief.org/patent/us/4237224/cohen-boyer-recombinant-dna **Original patent:** https://patents.google.com/patent/US4237224 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How Scientists Taught Bacteria to Make Human Hormones](https://patentbrief.org/patent/us/4356270/recombinant-dna-cloning-genentech) — Genentech's 1979 patent on using engineered DNA to force bacteria to produce human proteins like insulin and growth hormones. - [How Scientists Created Bacteria That Eat Oil Spills](https://patentbrief.org/patent/us/4259444/chakrabarty-genetically-modified-bacteria) — A 1981 patent for genetically engineered bacteria capable of breaking down multiple types of oil, which became the first living organism ever patented. - [Making Hybrid Antibodies from Different Animals](https://patentbrief.org/patent/us/4816567/recombinant-antibody-production-in-cho-cells) — This patent describes how to create new, engineered antibodies by combining parts of antibodies from two different animal species, then growing them in a lab. - [How to Make Human Erythropoietin (EPO) Using Engineered DNA](https://patentbrief.org/patent/us/4703008/neupogen-g-csf-filgrastim) — This patent describes the specific DNA sequences and methods to engineer cells to produce erythropoietin (EPO), a protein vital for red blood cell production, outside the human body. - [How to Make Many Copies of a Specific DNA Segment](https://patentbrief.org/patent/us/4683202/pcr-polymerase-chain-reaction-mullis) — This patent describes the fundamental three-step process for making millions of copies of a specific piece of DNA using short starter molecules and an enzyme, a technique known as Polymerase Chain Reaction (PCR).