In a prokaryotic organism, we would expect transcription to take place in the:
A Nucleoid
B Mitochondria
C Nucleus
D Ribosome
The correct answer and explanation is:
The correct answer is A. Nucleoid.
In prokaryotic organisms, such as bacteria, transcription occurs in the nucleoid. The nucleoid is an area within the cell that contains the organism’s genetic material, but it is not enclosed by a membrane like the nucleus in eukaryotic cells. Prokaryotes lack membrane-bound organelles, so their genetic material is freely located in the cytoplasm.
Transcription is the process by which an RNA molecule is synthesized from a DNA template. In prokaryotes, this process occurs in the nucleoid region, where the DNA is located. The RNA polymerase enzyme binds to specific regions on the DNA called promoters and then synthesizes the RNA strand in the 5′ to 3′ direction. After transcription, the RNA may immediately undergo translation into a protein in the cytoplasm, often even while the transcription process is still ongoing.
In contrast, eukaryotic organisms have membrane-bound organelles like the nucleus, where transcription occurs separately from translation. The mRNA produced in eukaryotes must also undergo further processing, including splicing, before leaving the nucleus to be translated in the cytoplasm.
Thus, in prokaryotes, the absence of a nucleus or other membrane-bound organelles allows the transcription and translation processes to occur simultaneously in the cytoplasm, directly in the nucleoid region.