Question

9. (5 pts, I preach) Circle all TRUE statements : (a). A transversion mutation generated during DNA replication must have had a purine-purine or a pyrimidine-pyrimidine pairing to occur. (b). In the ColEl plasmid copy control system, if one were to block RNA-1 transcription the copy number should decrease. (c) In E. coli UV light induces a higher mutation rate through induction of the SOS system. (d). RecA, LexA, and DNA polymerase I plays an essential role in activating the SOS response (e). UmuCD plays an essential role in translesion synthesis.

Answer 1

(a) TRUE

TRANSVERSION MUTATION Is a specific kind of point mutation, one in which a single purine is substituted for a pyrimidine or vice versa.

so a purine is substituted by a pyramidine result in pyramidine -pyramidine pair and when a pyramidine is replaced by a purine result in purine-purine pair.

b)TRUE

plasmid copy number mainly depend on The ori and its constituent ColE1 RNA I and RNA II .

so when the RNA I get blocked the number of plasmid copy decreases.

c)FALSE

UV radiation causes mutation of Ecoli .

mutation is repaired by the SOS system, it include RecA protein, LexA protein,DNA polymerase 1.

so this system reduces the effect of mutation by repairing.

d)TRUE

RecA protein, LexA protein,DNA polymerase 1 plays an essential role in the activation of SOS response.

e)TRUE

DNA Polymerase V (Pol V) is a polymerase enzyme involved in DNA repair mechanisms in prokaryotic bacteria, such as Escherichia coli. It is composed of a UmuD' homodimer and a UmuC monomer, forming the UmuD'2C protein complex