NEET BIOLOGY

Detailed explanation-1: -Coupled transcription-translation (CTT) is a hallmark of prokaryotic gene expression. CTT occurs when ribosomes associate with and initiate translation of mRNAs whose transcription has not yet concluded, therefore forming “RNAP. mRNA.

Detailed explanation-2: -Coupled transcription-translation (CTT) occurs when ribosomes bind and start to translate nascent mRNAs, whose transcription has not terminated yet, therefore forming an “RNAP·nascent mRNA·ribosome” complex (Figure 1).

Detailed explanation-3: -Both processes occur in the cytoplasm in prokaryotes. The factor controlling these processes is RNA polymerase in transcription and ribosomes in translation. In transcription, this polymerase moves over the template strand of DNA, while in translation, the ribosome-tRNA complex moves over the mRNA strand.

Detailed explanation-4: -The lack of a nuclear membrane that physically separates the chromosomal DNA from the cytosolic environment led to the well-accepted notion that transcription and translation are spatiotemporally coupled in bacteria and archaea.

Detailed explanation-5: -Prokaryotic transcription and translation can occur simultaneously. This is impossible in eukaryotes, where transcription occurs in a membrane-bound nucleus while translation occurs outside the nucleus in the cytoplasm.