Biotechnology uses living systems deliberately
Biotechnology applies organisms, cells, enzymes or genetic material to create useful products and processes. Modern medical biotechnology can isolate a single antigen, detect a particular molecule or DNA sequence, mass-produce a human protein, or deliver a functional gene to selected cells.
The common logic is specificity. A chosen gene, antibody or probe is matched to a defined biological target, allowing safer vaccines, precise tests and therapies aimed at a molecular cause.
Recombinant DNA turns cells into protein factories
A gene encoding a desired protein is isolated or synthesized, inserted into a vector such as a plasmid, and introduced into a host cell. Selectable markers help identify transformed cells, which are cloned and grown. Gene expression produces the protein, which must then be purified and tested.
Bacteria can produce proteins such as human insulin, but complex human proteins may require eukaryotic cells for correct folding and post-translational modification. Yeast, cultured mammalian cells or transgenic animals may therefore be used for particular products.
Choose the coding sequence for the product.
Join the gene to regulatory DNA in a carrier.
Introduce recombinant DNA into suitable cells.
Clone productive cells in controlled culture.
Separate and verify the therapeutic protein.
Vaccines can use selected antigens
Traditional vaccines may use weakened or inactivated organisms, while biotechnology can focus on selected antigenic components. A gene encoding an antigen can be expressed in yeast or another host, producing a recombinant subunit vaccine without growing the complete pathogen in the final product.
Peptide vaccines use selected antigen fragments, while newer platforms can deliver genetic instructions that cause host cells to make an antigen temporarily. Every platform must balance safety, stability, the strength and duration of immunity, and practical manufacturing.
Monoclonal antibodies are identical targeting tools
A monoclonal antibody preparation contains antibodies with the same specificity. Classical hybridoma production fuses an antibody-producing B lymphocyte with an immortal myeloma cell, creating a hybrid cell that can divide repeatedly while producing the desired antibody.
Monoclonal antibodies can detect hormones, microbial antigens or tumour markers. A pregnancy test, for example, uses antibodies that bind hCG. The signal depends on highly specific antigen–antibody interaction rather than on the antibody directly changing the patient's condition.
| Tool | Detects | Recognition principle |
|---|---|---|
| Monoclonal antibody | A specific antigen or other molecule | Three-dimensional epitope binding |
| DNA/RNA probe | A complementary nucleic-acid sequence | Base-pair hybridisation |
Nucleic-acid probes find complementary sequences
A probe is a labelled single-stranded nucleic-acid sequence designed to pair with a target. Sample nucleic acid is made accessible and single-stranded, the probe is allowed to hybridise, unbound probe is washed away, and the retained label indicates that a complementary sequence was present.
Probe specificity depends on sequence complementarity and hybridisation conditions. Modern amplification and sequencing methods extend this principle, but the central idea remains selective base pairing.
Gene therapy changes information inside cells
Gene therapy can add a functional gene, alter gene regulation or directly edit a sequence. In ex vivo therapy, cells are removed, genetically modified and tested before being returned. In vivo therapy delivers the vector directly to tissue inside the patient.
Viral vectors are efficient because viruses naturally enter cells, but they must be redesigned for safety and can trigger immune responses. Non-viral systems such as lipid particles may be safer or easier to manufacture but can deliver less efficiently. Lasting benefit also depends on reaching enough appropriate cells and controlling gene expression.
Remove cells → modify and test → return cells.
Deliver the vector directly into the patient.
Reach the right cells with safe, controlled expression.
The ideas to carry forward
- Recombinant hosts express selected genes to make useful proteins.
- Vaccines present antigens; antibodies recognise antigens.
- Monoclonal antibodies recognise molecules, while probes recognise complementary sequences.
- Gene therapy must solve delivery, specificity, expression and safety together.
Answer first. Then reveal the marking logic.
01Why might a therapeutic human protein be produced in a eukaryotic host rather than bacteria?2 marks · show the biological link
Answer: Some proteins require complex folding or post-translational modification that bacterial cells cannot perform correctly.
02What is the central difference between an antibody diagnostic and a DNA probe?2 marks · show the biological link
Answer: The antibody recognises a molecular epitope by shape and chemistry; the probe recognises a complementary nucleic-acid sequence by base pairing.
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