Salam Academy
Sign inCreate account
Learn7402Paper 2 · Paper 2: Topics 5–8The control of gene expressionGenetic engineering applications
The control of gene expression · Subtopic 2 of 3

Genetic Engineering Applications

Recombinant human proteins made by GM bacteria, yeast or animals: insulin, factor VIII (haemophilia), adenosine deaminase; purer and more plentiful than animal sources. Gene therapy adds a working allele to treat genetic disease (e.g. SCID, cystic fibrosis) using viral vectors or liposomes; somatic therapy affects only the patient, germ-line would be inherited (banned in humans). Genetic screening detects alleles (e.g. BRCA1, CF) with DNA probes; genetic counselling helps people decide. PGD screens IVF embryos. GM crops: Bt maize (insect resistance), herbicide-tolerant soya, Golden Rice (β-carotene for vitamin A). DNA profiling uses variable repeat sequences, PCR and electrophoresis for forensics and paternity. Ethical issues: safety, gene flow to wild plants, monopolies, consent, designer babies.

Cambridge 9700 Paper 4Edexcel YBI11 WBI15AQA 7402 Paper 2≈ 45 minRevision 1 · updated 2026-11-02
Section 1 of 14

Learning objectives

  • Describe uses of recombinant proteins.
  • Describe gene therapy and its challenges.
  • Describe genetic screening and profiling.
  • Evaluate GM crops and ethical issues.
Pause and think

Why does gene therapy for cystic fibrosis have to be repeated?

Section 2 of 14

Core idea

Start hereMedicine from microbes

The insulin keeping millions of people alive is made by genetically modified microorganisms.

The big idea

Gene technology provides proteins, therapies, tests and crops, but each use raises questions of safety and ethics.

Uses of gene technology

Benefits with matching concerns.

Worked exampleChance match

Three independent markers, each 1 in 20.

Goal
Probability of random match.
Strategy
Multiply.
  1. (120)3\left(\tfrac1{20}\right)^3
    Independent events.
  2. =18000=1.25×10−4=\tfrac1{8000}=1.25\times10^{-4}
    Evaluate.
Answer1 in 8000.
✓ CheckMore markers → rarer ✓.

Summary

  • Recombinant proteins.
  • Gene therapy.
  • GM crops; profiling; ethics.
Key words
Gene therapy
Inserting a functional allele to treat a genetic disorder.
DNA profiling
Comparing variable DNA regions to identify individuals.
HistoryFirst gene therapy. In 1990 four-year-old Ashanti DeSilva was treated for ADA-SCID by returning her own T cells after adding a working gene.
Fun factGlowing fish. GloFish, zebrafish carrying fluorescent protein genes, were the first GM pets sold to the public.
Keep reading for free

Create a free account to read the rest of this lesson: key formulae, worked examples, explore the graph, common mistakes, exam tip, guided practice and more. Your answers are checked and your progress is saved.

Create free accountSign in