Why can translation occur immediately after transcription in prokaryotes?

Sourav PanNovember 9, 2024

Answered step-by-step

Translation can occur immediately after transcription in prokaryotes due to several key factors related to their cellular structure and the nature of their genetic processes:

1. Lack of Compartmentalization

• Cytoplasmic Location: In prokaryotic cells, the DNA is located in the cytoplasm within a region called the nucleoid. Unlike eukaryotes, which have a defined nucleus that separates transcription (in the nucleus) from translation (in the cytoplasm), prokaryotes do not have such membrane-bound compartments. This spatial organization allows transcription and translation to occur simultaneously in the same cellular environment.

2. Coupled Transcription and Translation

• Simultaneous Processes: As soon as RNA polymerase begins transcribing a gene into mRNA, ribosomes can attach to the nascent mRNA strand and start translating it into protein, even before transcription is complete. This phenomenon is known as coupled transcription-translation (CTT). The ribosomes bind to specific sequences on the mRNA, such as the Shine-Dalgarno sequence, facilitating immediate translation.

3. Directionality of Processes

• 5′ to 3′ Direction: Both transcription and translation occur in the same 5′ to 3′ direction. This alignment allows ribosomes to “chase” RNA polymerase as it synthesizes mRNA, enabling efficient use of newly formed mRNA for protein synthesis .

4. Efficiency in Gene Expression

• Rapid Response: The ability to couple these processes allows prokaryotic cells to quickly respond to environmental changes by rapidly producing proteins as needed. This efficiency is particularly advantageous for single-celled organisms that must adapt swiftly to their surroundings