BMS 113 · Common Core (Tronc commun)Section 2.3 · Sources of drugs
Section 7 of 31
Biotechnology and genetic engineering
Explain how living cells are used to make medicines, and name the main products of biotechnology.
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Why this matters
If you skip this, you may think every medicine is either extracted from nature or built purely by chemistry, and miss a third route that now supplies insulin, growth hormone and vaccines. The section also explains why biological products carry their own manufacturing risks, and it links forward to Unit 2.5, where they must pass the same approval pipeline.
What you need to know first
You should already know that a gene carries the instructions for building a protein, and that bacteria and yeasts are living cells that can be grown in a vessel. Unit 2.2 introduced fermentation and the microbial risk of biological material.
Words to know (5)
Biotechnology
Using living cells or their products to make substances that benefit human beings. Human insulin made in yeast is a product of biotechnology.
Recombinant DNA
A new DNA strand made by combining two different DNA strands, for example a human gene and a bacterial DNA. The human insulin gene placed in E. coli is recombinant DNA.
Genetic engineering
The branch of biotechnology that changes the genetic instructions of a cell. Genetic engineering gave yeast the instructions to make a human protein.
Monoclonal antibody
An identical antibody made by one laboratory cell line and aimed at one specific target. Rituxan is a monoclonal antibody used against some cancers.
Host cell
The living cell that receives a foreign gene and then manufactures the protein that the gene codes for. E. coli can act as the host for the human insulin gene.
One idea at a timeIdea 1 / 4
In one sentence Biotechnology makes medicines by instructing a living cell, such as a bacterium or a yeast, to manufacture the substance.
Biotechnology uses living cells as factories
Biotechnology is the use of living cells or their products to make substances that benefit human beings. Instead of extracting a medicine from a plant or an animal, biotechnology instructs a living cell — a bacterium or a yeast — to manufacture it. The cell is grown in a controlled vessel, supplied with nutrients, and the substance it produces is harvested and purified. This is a distinct kind of source: it is neither natural in the old sense nor purely synthetic, because a living organism performs the chemistry under human direction. Its advantage is that the product can be made identical to the human substance and produced in quantity, without depending on a harvest or on donors.
For example
A vat of genetically instructed yeast can produce a human protein continuously, whereas extracting the same protein from human tissue would depend on scarce donations.
Think of it like
A cell used this way is like a small factory that can be given a new recipe: it will build the product from the instructions it holds. The limit is that a living factory can also fail, become contaminated or read the recipe weakly, so the product must still be tested and purified.
Pause and check yourself
What makes biotechnology different from extracting a drug from a plant?
Show the answer
A living cell is directed to build the medicine, instead of the medicine being taken out of plant or animal material.
Read detailed explanations
How a gene becomes a medicine
A gene is a set of chemical instructions for building a protein. Biotechnology borrows that instruction and gives it to a cell that grows quickly and cheaply. The first step is to identify the protein that the patient needs — for example insulin, human growth hormone, or the protein used in the recombinant hepatitis B vaccine. The second is to find and copy the gene that codes for it. The third is to combine that gene with the DNA of a host, which is what recombinant DNA means: two different DNA strands combined to produce a new strand of DNA. The fourth is to introduce the recombinant DNA into a host such as E. coli or yeast and grow the host. The host does not know that the gene is foreign; it reads it and builds the human protein as part of its normal activity. Finally the protein is extracted and purified. Each step has its own failure modes — the gene may be expressed weakly, the host may be unstable, or the purification may not remove all impurities — which is why biological medicines need rigorous manufacturing control.
Monoclonal antibodies: one target, two uses
An antibody is a protein the immune system uses to recognise a specific target. A monoclonal antibody comes from hybrid cells created in the laboratory from animals, and because the line descends from a single cell, every molecule it produces is identical. That uniformity is the whole point: a conventional antibody preparation is a mixture recognising many targets, whereas a monoclonal preparation recognises one. This gives the product two distinct uses. In treatment, it can be aimed at a marker found mainly on tumour cells, so the effect is directed towards those cells rather than spread through the body; Rituxan, Zevalin, Erbitux and Avastin are examples used in the treatment of various cancers. In diagnosis, the same specificity makes it a precise detector, because binding to its target can reveal the presence or the location of a substance. The word to remember is specificity — one antibody, one target — and it explains both the promise of targeted therapy and the cost of manufacture, since each product needs its own living cell line and strict biological control.
Explore the diagram
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Biotechnology: making medicine with cells
Two parallel manufacturing routes: recombinant DNA inside a host cell for human proteins, and cell fusion for monoclonal antibodies.
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01 / 9Human gene (the donor)
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Human gene (the donor)
Route A begins with a human gene — the DNA sequence that codes for insulin or for human growth hormone. The gene is cut out of human DNA with enzymes and becomes the insert carrying the instructions that the host cell will read as if they were its own.
Schematic flow; not to scale. The steps are simplified and several purification, quality-control and formulation stages are omitted.
Key points to remember
✓Biotechnology uses living cells as factories, so its products are neither extracted from nature nor purely synthetic.
✓Recombinant DNA combines two DNA strands so that a microbe can read a human gene and make a human protein.
✓Human insulin, human growth hormone and the recombinant hepatitis B vaccine are products of this method.
✓Monoclonal antibodies come from one hybrid cell line, recognise one target, and are used in cancer treatment and diagnosis.
Go deeper
Worked example
Following a gene from patient to product. A patient with diabetes needs insulin that does not come from an animal pancreas. Your teacher asks you to explain, step by step, how biotechnology can supply a human protein and why this is safer than taking it from an animal.
Identify the protein the patient needs: in diabetes the missing effect is that of insulin.
Find the human gene that carries the instructions for that protein, and combine it with the DNA of a host microorganism — recombinant DNA, combining two different DNA strands to form a new strand.
Insert the recombinant DNA into a host such as E. coli or yeast, which will read the human gene as its own and produce the human protein.
Grow the host in a controlled vessel so that it multiplies and accumulates the protein, then harvest and purify the product.
Compare with the animal route: insulin taken from the pancreas of pigs and cows depends on animal tissue, which is more likely to be contaminated with pathogenic microbes.
Biotechnology replaces extraction with instruction: a living cell makes the human protein, and the supply no longer depends on animal tissue. The same logic produces human growth hormone and the recombinant hepatitis B vaccine.
Common misconception
Biotechnology is sometimes imagined as copying an existing drug more cheaply. It is better understood as instructing a living cell to make a substance — often a human protein that could not be extracted in useful quantities, such as insulin, growth hormone or a vaccine protein.
Check your reasoning
Why does producing human insulin in bacteria reduce a safety risk compared with insulin from pig or cow pancreas?
Reveal an answer
Because the product no longer depends on animal tissue, which the lecture notes describe as more likely to be contaminated with pathogenic microbes. The engineered host makes a protein identical to the human one in a controlled culture, so the raw material is defined and the risk of carrying animal infectious agents is removed.
Where this comes from
BMS 113 General Pharmacology I lecture notes · Unit 2, p. 12
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About this course and its sources
Bilingual lessons organised from the supplied BMS 113 General Pharmacology I lecture notes. Diagrams are original educational schematics; pharmacology, nursing and French-language review are pending.