Emerging biotechnologies — A/L Biology

How do I practise Emerging biotechnologies?

1 question with a worked solution

1. In the CRISPR-Cas9 targeted genome editing technology, what component specifically guides the Cas9 endonuclease to introduce a double-strand break at the intended genomic DNA locus?
   1. A) Zinc-finger transcription factor recognizing double-stranded palindromes
   2. B) Taq DNA polymerase recognizing the Pribnow box
   3. C) Single guide RNA (sgRNA) containing a matching sequence complementary to the target DNA
   4. D) Reverse transcriptase synthesized by retroviral vectors
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   Correct answer: C) Single guide RNA (sgRNA) containing a matching sequence complementary to the target DNA

   The CRISPR-Cas9 genome editing platform utilizes an engineered single guide RNA (sgRNA) that pairs via standard Watson-Crick base-pairing with a 20-nucleotide target sequence in the genomic DNA. The guide RNA directs the Cas9 endonuclease, which creates a site-specific double-strand break (DSB) next to the protospacer adjacent motif (PAM).

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   Step 1: Understand CRISPR-Cas9 system components: - Cas9: Molecular scissors (endonuclease that cuts double-stranded DNA). - sgRNA (single guide RNA): 20-nt complementary guide specifying target cutting locus. - PAM: Protospacer adjacent motif required for Cas9 recognition. Answer: Single guide RNA (sgRNA) containing a matching sequence complementary to the target DNA.
   Modelled on: the A/L Biology examination pattern

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Where does Emerging biotechnologies fit in the syllabus?

Year 2 · Term 3