Options (A), (B), and (D) are correctly paired, while (C) is incorrect. DnaA initiates bacterial DNA replication, RecA mediates homologous recombination, and sigma factor enables transcription initiation, but Rho factor handles transcription termination rather than DNA repair.

Option Analysis

Replication: DnaA
DnaA protein binds to the origin of replication (oriC) in bacteria like E. coli, unwinds DNA, and recruits helicase to start replication. This pairing is correct as DnaA controls replication initiation timing and frequency.

Recombination: RecA
RecA forms nucleoprotein filaments on single-stranded DNA, enabling homologous sequence search, strand invasion, and repair via homologous recombination. It also activates the SOS response for DNA damage. This pairing holds true.

DNA repair: Rho factor
Rho factor is an RNA helicase that terminates transcription by dislodging RNA polymerase from DNA templates. While it may indirectly aid repair by clearing stalled polymerases at lesions, its primary role is transcription termination, not direct DNA repair like Uvr proteins or RecA. This pairing is incorrect.

Transcription: Sigma factor
Sigma factors bind RNA polymerase core enzyme, recognize promoter sequences, melt DNA, and initiate transcription. This essential role in bacterial gene expression makes the pairing correct.

In CSIR NET Life Sciences preparation, mastering Replication DnaA Recombination RecA DNA repair Rho Transcription Sigma pairings is crucial for molecular biology questions. These concepts test understanding of prokaryotic DNA processes, vital for exams like CSIR NET.

Core Functions

• DnaA in Replication: Initiates at oriC by binding DnaA boxes, melting DNA, and loading DnaB helicase.

• RecA in Recombination: Drives strand exchange for homologous recombination and SOS-induced repair.

• Rho Factor Reality: Terminates transcription, not primary DNA repair; aids indirectly by recycling stalled RNAP.

• Sigma in Transcription: Targets promoters, forms open complex for RNA synthesis start.