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1.3 Mutagenesis, Knockout & Sequencing — Test 1
Q1. Sanger (dideoxy) DNA sequencing relies on chain termination by:✓ Dideoxynucleotides (ddNTPs)
Q2. A dideoxynucleotide terminates DNA synthesis because it lacks a:✓ 3'-hydroxyl group
Q3. The Maxam-Gilbert method of DNA sequencing is based on:✓ Base-specific chemical cleavage of DNA
Q4. In modern automated sequencing, the four ddNTPs are distinguished by:✓ Different fluorescent dyes detected during capillary electrophoresis
Q5. Site-directed mutagenesis is a technique used to:✓ Introduce a specific, predetermined change at a defined position in a gene
Q6. A gene knockout experiment is designed to:✓ Inactivate (disrupt) a specific gene to study its function
Q7. Knockout mice are classically generated by introducing a disrupted gene into embryonic stem cells via:✓ Homologous recombination
Q8. In the CRISPR-Cas9 system, the component that directs Cas9 to its target DNA sequence is the:✓ Guide RNA (gRNA)
Q9. The Cas9 enzyme in genome editing acts as a:✓ Nuclease that creates a double-strand break
Q10. The Cre-loxP system is used to achieve:✓ Site-specific recombination (e.g. conditional knockouts)
Q11. A 'knock-in' differs from a 'knockout' in that a knock-in:✓ Inserts a specific gene or sequence at a defined locus
Q12. Zinc-finger nucleases (ZFNs) and TALENs are tools for:✓ Targeted genome editing (programmable DNA cutting)
Q13. Random (untargeted) mutagenesis can be induced by:✓ UV light or chemical mutagens
Q14. The shotgun strategy for genome sequencing involves:✓ Randomly fragmenting the genome, sequencing the pieces, then assembling overlaps
Q15. Sanger sequencing requires, in addition to the template, a:✓ Primer to provide a free 3'-OH for the polymerase
Q16. Oligonucleotide-directed (site-directed) mutagenesis introduces the mutation through a:✓ Synthetic primer carrying the altered sequence
Q17. After Cas9 makes a double-strand break, a gene is most often disrupted (knocked out) when the cell repairs it by:✓ Error-prone non-homologous end joining (NHEJ)
Q18. Detection of post-translational modification of proteins, such as phosphorylation, is commonly done using:✓ Modification-specific antibodies (e.g. on Western blots) or mass spectrometry
Q19. A key advantage of CRISPR-Cas9 over earlier editing tools (ZFNs, TALENs) is that targeting is reprogrammed simply by:✓ Changing the short guide RNA sequence
Q20. Match each tool with its function and select the correct option.✓ A-ii, B-iv, C-i, D-iii