Question

tnpA res tnpR bla Tn3 Consider the complex transposon in the above illustration. Suppose you discover a derivative of this element that replicatively inserts into target DNA but then becomes "stuck" as part of a cointegrate. Your graduate student sequences the respective gene products and finds no change in the primary amino acid sequences of the encoded enzymes. In which locus must the defect lie? Choose one: A. res B. tnpA C. in one (or both) of the inverted repeats D. tnpR E. bla

Answer 1

Answer: res

Explanation:

• If there are no change in the primary amino acid sequence then the problem lies with the resolution site (res).
• tnpA =  transposase, tnpR =  resolvase, bla = β-lactamase.
• All the above mentioned genes codes for a protein.
• Res is a specific site in which resolvase executes site-specific recombination.
• It does not code for any protein.
• Its a site for resolvase to act upon.
• Defect in res or tnpR can lead to non-resolution of cointegrate structure.
• Here in this scenario, there are no change in the primary amino acid sequence. Hence it rules out tnpR.
• So defect lies with res.