Where does the transcription occur in a prokaryotic cell?

Appeared in: RIMS Nursing Officer - 2022

Explanation

Cytoplasm.
Prokaryotic cells lack a membrane-bound nucleus; their genetic material (DNA) is located in a region of the cytoplasm known as the nucleoid.
Since the DNA and the necessary enzymes (like RNA polymerase) are both in the cytoplasm, transcription must occur there.
A unique feature of prokaryotes is that transcription and translation can happen simultaneously because there is no nuclear membrane separating the DNA from the ribosomes.

Option A: Prokaryotic cells are defined by their lack of a nucleus. The nucleus is where transcription occurs in eukaryotic cells, not prokaryotic cells.
Option C: Vacuoles are organelles for storage and waste management; they are not involved in genetic processes like transcription. Also, prokaryotes typically do not have true vacuoles.
Option D: Mitochondria are organelles found in eukaryotic cells that are responsible for cellular respiration. Prokaryotic cells do not have mitochondria.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Location of Transcription in Prokaryotic Cells as background academic context rather than a clinical decision trigger.
Understanding the fundamental differences between prokaryotic (bacterial) and eukaryotic (human) cells is the cornerstone of antimicrobial therapy.
Many antibiotics, such as rifampin, specifically target prokaryotic RNA polymerase to inhibit transcription, thereby killing the bacteria without harming the patient's eukaryotic cells.
Other antibiotics target the 70S ribosomes found in bacteria, which are structurally different from the 80S ribosomes in human cells, to block protein synthesis.

How to Approach the Question

First, identify the key terms in the question: 'transcription' and 'prokaryotic cell'.
Recall the definition of a prokaryotic cell. The defining feature is the absence of a membrane-bound nucleus.
Understand that transcription is the process of reading DNA. Therefore, transcription must happen where the DNA is located.
Combine these two facts: In a prokaryotic cell, the DNA is in the cytoplasm (in the nucleoid region). Therefore, transcription must also occur in the cytoplasm.
Evaluate the options based on this reasoning. Eliminate options like 'Nucleus' and 'Mitochondria' as they are not present in prokaryotic cells.

Concept Tested & Keywords

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E6 Microbiology Applied AnjuDhir 3e Part 1 p. 63-65

E6 Biochemistry U Satyanarayana— Part 2 (pp 421-820 of 840) p. 176-178

Practise the full RIMS Nursing Officer - 2022

Attempt every question from this paper in a timed mock, then review the full solution for each one.