6. cis-acting operator DNA sequences generally display:
- symmetry
- dyad symmetry
- super symmetry
- no symmetry
- none of the above
7. cDNA cloning:
- requires the enzyme reverse transcriptase
- does not require ligation
- requires genomic DNA
- requires bacteriophages
- does not require thought
8. The formation of the 2:3 stem-loop in the trpL leader RNA of the E.coli trp operon:
- prevents attenuation of the trp operon
- is facilitated when Trp levels in the cell are low
- all of the above
- prevents the formation of the 3:4 stem loop
- occurs when the ribosome stalls in trpL
9. To express a eukaryotic gene in a bacterium:
- B. firstly cDNA has to be synthesised from the mature mRNA before cloning the gene
- all of the above
- A. a bacterial expression vector must be used
- A and B
- C. the genomic DNA first needs to be cloned from the eukaryotic genome
10. Mutation of an adenine bas to guanine base in DNA is called...
- a frameshift mutation
- a silent mutation
- a transition mutation
- a transversion mutation
11. Mutations in the Lacl gene, encoding the Lacl repressor proteins:
- prevent growth of lactose
- all of the above
- prevent binding of RNA polymerase
- generally lead to constitutive expression of the lac operon
- are cis-dominant
12. which codon serves as the start codon in mRNA for translation?
- AUG
- UGG
- AGU
- UGA
13. transposons:
- have inverted repeats at each end
- all of the above
- encode a transposase enzyme
- generate a small tandem sequence duplication when they transpose
- can generally insert into any DNA sequence
14. When E.coli is grown on a mixture of lactose and glucose?
- lactose is used first
- glucose is used first
- lactose and glucose are used at the same time
- lactose is never used
- lactose represses glycolysis
15. The ligand that binds to the E.coli CRP (CAP) protein is:
- tryptophan
- cycteine
- glucose
- cyclic AMP
- arabinose
16. How many different transcription factors are bound to the E.coli lac operon promoter region when both lactose and glucose are present in the growth medium?
- 2
- 4
- none
- 3
- 1
17. The trp operon attenuation mechanism..
- relies on the coupling of transcription and translation
- relies on the coupling of replication and translation
- relies on the coupling of replication and translation
- requires the binding of the TrpR repressor
18. Generalised recombination:
- is an additive process
- involves site specific recombination
- does not require RecA protein
- requires extensive sequence similarity between two DNA sequences
- involves the enzyme transposase
19. The ligand that binds to E.coli Lacl repressor is:
- lactose (allolactose)
- cyclic AMP
- galactose
- glucose
- glycerol
20. Mutations in lacO, the operator of the lac operon prevent:
- binding of CRP
- none of the above
- binding of Lacl repressor
- expression of the lac operon
- binding of RNA polymerase
