BIOLOGY WITH HAMZA · MDCAT REVISION
Biotechnology
Name: ____________________ Date: ______________
Recall first. Check second. Return to the ideas you missed.
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Learning targets
- Explain how cloned genes produce antigens and therapeutic proteins.
- Compare monoclonal-antibody and nucleic-acid-probe diagnostics.
- Distinguish ex vivo from in vivo gene therapy and their vector challenges.
Core notes
- 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.
Read, cover and redraw
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.
Written recall
1. Why might a therapeutic human protein be produced in a eukaryotic host rather than bacteria?
2. What is the central difference between an antibody diagnostic and a DNA probe?
3. Two targets, five ideal cycles: how many copies?
4. Why reverse transcribe RNA?
5. Can a no-template control validate collection quality?
Apply the idea
1. Starting with 5 double-stranded DNA molecules, an ideal PCR doubles the target each cycle. How many target molecules are present after 6 cycles?
- 320
- 64
- 160
- 30
My answer: _____ Reason: ____________________________________
2. Which DNA fragment is expected to migrate farthest from the wells in a standard agarose gel when other conditions are the same?
- 900 base pairs
- 300 base pairs
- 1,800 base pairs
- 3,000 base pairs
My answer: _____ Reason: ____________________________________
3. A plasmid carries ampicillin resistance. Colonies grow on ampicillin after transformation. What remains unproven by growth alone?
- Whether they have produced visible descendants
- Whether they can survive the antibiotic conditions used
- Whether the colonies carry the intended DNA insert
- Whether growth occurred on that plate
My answer: _____ Reason: ____________________________________
Answer key
Cover this section while attempting the questions.
Written recall
1. Some proteins require complex folding or post-translational modification that bacterial cells cannot perform correctly.
2. The antibody recognises a molecular epitope by shape and chemistry; the probe recognises a complementary nucleic-acid sequence by base pairing.
3. 2 × 2⁵ = 64.
4. Ordinary PCR amplifies DNA.
5. No. It checks contamination in the amplification setup.
Applied questions
1. A — Ideal amplification follows N = N₀×2ⁿ. Here, 5×2⁶ = 320. Real reactions may amplify less efficiently and eventually reach a plateau.
2. B — Smaller DNA fragments generally move more easily through the gel matrix. DNA migrates towards the positive electrode because of its negatively charged phosphate backbone.
3. C — Antibiotic selection supports possession or expression of the resistance marker. An empty vector can also confer resistance, so the desired insert requires separate screening.