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1.2 Molecular Cloning & Vectors — Test 1
Q1. The substrate on which a restriction endonuclease acts is:✓ Double-stranded DNA
Q2. A staggered (offset) cut by a restriction enzyme on the two DNA strands produces:✓ Cohesive (sticky) ends
Q3. DNA ligase joins DNA fragments by forming a:✓ Phosphodiester bond
Q4. Which property must every cloning vector possess?✓ An origin of replication
Q5. A selectable marker most commonly carried by a plasmid cloning vector is a gene for:✓ Antibiotic resistance
Q6. In blue-white screening, recombinant (insert-containing) colonies appear:✓ White
Q7. A cosmid is a cloning vector that combines a plasmid with the:✓ cos site of phage lambda
Q8. Which vector accommodates the LARGEST DNA inserts?✓ Yeast artificial chromosome (YAC)
Q9. A bacterial artificial chromosome (BAC) is based on which natural element of E. coli?✓ The F (fertility) plasmid
Q10. To make bacterial cells competent for taking up plasmid DNA, a common chemical method uses:✓ Calcium chloride and a brief heat shock
Q11. Reverse transcriptase synthesises:✓ DNA from an RNA template
Q12. A cDNA library differs from a genomic library in that cDNA clones:✓ Lack introns (represent only expressed mRNA)
Q13. T4 polynucleotide kinase is used in cloning to:✓ Add a phosphate to the 5' end of DNA
Q14. In agarose gel electrophoresis, DNA fragments are commonly visualised using:✓ Ethidium bromide (or a similar DNA-binding dye)
Q15. Phage lambda used as a replacement vector accepts foreign DNA in place of its:✓ Non-essential central (stuffer) region
Q16. An expression vector, unlike a simple cloning vector, must additionally provide a:✓ Promoter and ribosome-binding site for the insert
Q17. Alkaline phosphatase is used during cloning to treat the vector so that it:✓ Cannot self-ligate (recircularise without an insert)
Q18. The recognition sequences of most type II restriction enzymes are:✓ Palindromic
Q19. The Ti plasmid, widely used to transfer genes into plants, is obtained from:✓ Agrobacterium tumefaciens
Q20. Match each cloning vector with its approximate maximum insert capacity and select the correct option.✓ A-iii, B-iv, C-i, D-ii