Combined effects of rifampin and streptomycin on bacterial protein synthesis

Steps:

• Rifampin binds to RNA polymerase, blocking transcription and preventing new mRNA synthesis.
• Streptomycin binds to the ribosome during translation, causing misreading of mRNA codons and producing faulty proteins.
• Immediate effect of rifampin: transcription stops, halting production of new mRNA.
• Immediate effect of streptomycin: translation of existing mRNA continues but generates erroneous proteins; translation is not fully inhibited.

Why B is correct:

• Rifampin inhibits transcription by binding RNA polymerase (per molecular biology definition of antibiotic mechanisms), while streptomycin induces translation errors without stopping it, matching effects 1 and 2.

Why the others are wrong:

• A includes 3, but streptomycin causes translation errors, not inhibition.
• C includes 3 but excludes 2, ignoring faulty protein synthesis from streptomycin.
• D excludes 1, overlooking rifampin's block of transcription.

Final answer: B