Question32 Which one of the following statements describes a key difference between transcription as it occurs in bacteria compared to eukaryotes? Select one alternative: Bacterial translation can start before transcription of the same gene has finished. Bacteria use three distinct RNA polymerases that synthesise different RNA types. In bacteria, synthesis of the RNA chain occurs in the 5′ → 3′ direction. Promoter regions are only found in bacterial operons. ResetMaximum marks: 1 Flag question undefined

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BlackTom AI · Accepted Answer

To approach this question, I will evaluate each statement in terms of what distinguishes bacterial transcription-translation from eukaryotic processes.
Option 1: 'Bacterial translation can start before transcription of the same gene has finished.' This captures a fundamental prokaryotic feature: transcription and translation are coupled because there is no nuclear membrane separating them. As soon as mRNA begins to emerge from RNA polymerase, ribosomes can bind and start translating, so translation can begin before transcription is completed. This is a real and well-established difference between bacteria and eukaryotes.
Option 2: 'Bacteria use three distinct RNA polymerases that synthesise different RNA types.' In bacteria, there is a single RNA polymerase responsible for synthesizing all RNA types, albeit with different sigma factors guiding initiation. The statement erroneously asserts there are three distinct polymerases, which is a hallmark of eukaryotes (where RNA Pol I, II, III synthesize different RNAs). Therefore this option is incorrect as a description of bacterial transcription.
Option 3: 'In bacteria, synthesis of the RNA chain occurs in the 5′ → 3′ direction.' While 5′→3′ directionality is true for RNA synthesis in most organisms, this is not a distinctive difference between bacteria and eukaryotes because both types of cells synthesize RNA in the 5′→3′ direction. Since the question asks for a key difference, this statement does not capture a differentiating feature.
Option 4: 'Promoter regions are only found in bacterial operons.' Promoter regions exist in both bacteria and eukaryotes and are not limited to bacterial operons; in bacteria promoters control individual genes or operons, and eukaryotic promoters function for individual genes and complex regulatory regions. Therefore this claim is incorrect as a general statement about promoters.
Overall, the statements differ in accuracy and in whether they reflect a true, distinguishing feature of bacterial transcription-translation coupling versus the eukaryotic system. The first option uniquely describes the coupled transcription-translation phenomenon characteristic of bacteria, whereas the others either misstate bacterial biology or describe non-distinguishing facts.

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