Question

Which of the following comparisons of prokaryotic transcription and eukaryotic transcription is incorrect?

Prokaryotic transcription	Eukaryotic transcription
a) Transcription unit has only one gene	Transcriptional unit has one or more genes
b) Occurs in the cytoplasm	Occurs in the nucleus
c) A single RNA polymerase synthesizes all the three types of RNA	The RNA polymerase I, II and III synthesize rRNA, mRNA and tRNA respectively
d) Coupled-transcription translation is the rule	Coupled transcription translation is not possible

A) (a)
B) (b)
C) (c)
D) (d)

Answer 1

The expression of genes in bacteria is regulated by extracellular signals that are often found in the medium in which bacteria grow. Regulatory proteins deliver these signals to the genes.

Complete answer:
First we should know about transcription to answer this question. Transcription is a mechanism by which an intermediate molecule, i.e. RNA is copied from the genetic material present in the DNA. The RNA sequence is complementary to that of the transcribed gene, and thus the RNA preserves the same material as the gene itself. Transcription in the living world is a common mechanism that happens in all prokaryotes and eukaryotes.
Now, let us find the solution from the options-

More than one gene is frequently covered in prokaryotic transcription and generates polycistronic mRNAs specifying more than one protein.
Prokaryotic transcription happens in the cytoplasm and eukaryotic transcription happens in the nucleus and translation occurs in the cytoplasm. Thus, the option B is incorrect.
In prokaryotic transcription, a single RNA polymerase can produce all the three forms of RNA and in eukaryotic transcription, three types of RNA polymerase is needed to produce three forms of RNA. Thus, the option C is incorrect.
In prokaryotic transcription, coupled-transcription translation is possible and in eukaryotic transcription, coupled-transcription translation is not possible. Thus, the option D is incorrect.

Thus, the correct answer is option A (a)

Note: Although eukaryotes and prokaryotes differ in a few unique aspects of transcription, the fundamental chemistry underlying the mechanism is the same. Both use RNA polymerase to induce RNA synthesis as a catalyst, and although the regulation can be different. RNA is the end product of transcription in prokaryotes and eukaryotes.