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6.3 Screening & Expression β Test 1
Q1. The most efficient and versatile gene-editing technology is based on:β CRISPR-Cas9
Q2. Applications of Southern blotting include:β All of these
Q3. Best E. coli strain for expressing a protein that needs disulphide bonds:β BL21(DE3) Origami (oxidising cytoplasm)
Q4. CRISPR-Cas9 is best described as:β An enzyme that cuts DNA at a site specified by a guide RNA
Q5. A 'zoo blot' (cross-species Southern) is used to:β Detect conserved (similar) sequences across different animal species
Q6. Heating a Southern-blot DNA probe (~65β95Β°C) before hybridization is done to:β Denature the probe to single strands so it can anneal to target
Q7. Single-stranded DNA probes are best generated by:β Asymmetric PCR (unequal primer ratio)
Q8. Green fluorescent protein (GFP) was originally isolated from:β Aequorea victoria (jellyfish)
Q9. Hybridization of single-stranded nucleic acids is favoured by:β Low temperature and high salt
Q10. In pBluescript, the cloned gene's transcription is under the control of:β T3/T7 promoters (flanking the MCS)
Q11. Localization of specific mRNA WITHIN cells/tissue is done by:β In situ hybridization
Q12. The most sensitive detection chemistry in real-time PCR is generally:β Hydrolysis (TaqMan) probes / molecular beacons
Q13. A probe is:β A short labelled DNA or RNA complementary to the target sequence
Q14. Protein-DNA interactions (shifted complexes) are best resolved on:β Native (non-denaturing) gel electrophoresis
Q15. RAPD analysis detects variation in:β DNA sequence revealed by PCR with random (arbitrary) primers
6.3 Screening & Expression β Test 2
Q16. Identify proteins that bind DNA based on retarded migration of DNA in a gel:β Gel retardation (EMSA / mobility shift)
Q17. Guide RNA in CRISPR-Cas9 functions to:β Target Cas9 to a specific DNA sequence by base pairing
Q18. The biggest advantage of CRISPR-Cas9 is that it:β Requires only a new guide RNA per target
Q19. DAPI, a blue DNA-binding dye, has excitation/emission maxima near:β 358/461 nm
Q20. Methods to locate the transcription start site include:β Primer extension and S1 nuclease mapping
Q21. The presence/distribution of specific mRNAs within a cell is detected by:β In situ hybridization
Q22. When using E. coli to express a mammalian protein, cDNA is preferred because:β Bacteria cannot splice out the introns in genomic DNA
Q23. Which CRISPR system (class/type) is most used for genome editing?β Type II (Cas9)
Q24. Which is TRUE about nucleic-acid hybridization stringency?β Excess NaCl decreases stringency (stabilises duplexes)
Q25. Which cloning vector does NOT contain a promoter upstream of the reporter (you supply/test the promoter)?β Promoter-test (promoter-less reporter) vector
Q26. Which E. coli strain is used to express genes under a T7 promoter?β BL21(DE3) (carries T7 RNA polymerase)
Q27. Microarray technology is based on:β Hybridization of labelled cDNA/cRNA to immobilized probes
Q28. Which is NOT a protein-detection method?β Fluorescence in situ hybridization (FISH β detects nucleic acids)
Q29. Which information CANNOT be obtained from a traditional Northern blot?β The amino-acid sequence of the encoded protein
Q30. Which is true of bacterial CRISPR systems in vivo?β They protect bacteria from phage, record infection history, and guide Cas to invaders β all of these
6.3 Screening & Expression β Test 3
Q31. CRISPR-Cas9 technology is widely used for:β Gene editing
Q32. CRISPR spacer/target sequences are recognised by:β The guide RNA (base pairing)
Q33. The correct order for DNA fingerprinting is:β Sample β extraction β restriction digestion β electrophoresis β membrane transfer β hybridize with probe
Q34. The reverse-genetics method of inactivating an endogenous gene to study its function is:β Reverse genetics (e.g. knockout/knockdown)
Q35. Far-Western blotting detects:β Protein-protein interactions (probe with a labelled bait protein)
Q36. Quantitative levels of a specific RNA are measured by:β RNase protection / Northern / qRT-PCR
Q37. In an EMSA giving three shifted bands from a muscle nuclear extract, the explanation could be:β Any of these could explain it
Q38. DNA footprinting determines:β The DNA region protected by a bound protein
Q39. Which is NOT true about cDNA?β It can be used to build a COMPLETE genomic library
Q40. Blotting techniques matched correctly are:β DNA with DNA probe = Southern; RNA with DNA probe = Northern; protein with protein probe = Far-Western
Q41. The general DNA-profiling workflow is:β DNA isolation β restriction digestion β electrophoresis β Southern blot β hybridization β analysis
Q42. Asymmetric PCR is used to generate:β Predominantly single-stranded DNA (for probes/sequencing)
Q43. GFP is most useful as a:β Reporter for gene expression/protein localization (visualised by fluorescence)
Q44. A promoter-test (reporter) vector measures:β The strength/activity of a cloned promoter via reporter output
Q45. To express a toxic protein, leaky basal expression is minimised using strains/plasmids such as:β BL21(DE3) pLysS (T7 lysozyme suppresses basal T7 pol)