Question:medium
Mechanism of action of actinomycin D is?
Mechanism of action of actinomycin D is?
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It intercalates into DNA and blocks RNA polymerase, halting transcription.
Updated On: Jun 24, 2026
- Inhibits DNA dependent RNA synthesis
- Activates DNA dependent RNA synthesis
- Inhibits RNA dependent DNA synthesis
- Activates RNA dependent DNA synthesis
Show Solution
The Correct Option is A
Solution and Explanation
Step 1: The task is to identify how the antitumour antibiotic actinomycin D kills cancer cells.
Step 2: Actinomycin D slides flatly between adjacent base pairs of DNA, a process called intercalation, anchoring tightly at guanine-cytosine sites. This distorts the DNA template.
Step 3: With the antibiotic lodged in the helix, RNA polymerase can no longer read the DNA, so the making of RNA from a DNA template (transcription) is shut down. Thus actinomycin D inhibits DNA-dependent RNA synthesis.
Step 4: It neither stimulates transcription nor touches the RNA-to-DNA reverse transcription pathway, ruling out the other three options.
\[\boxed{Inhibits\ DNA\ dependent\ RNA\ synthesis}\]
Step 2: Actinomycin D slides flatly between adjacent base pairs of DNA, a process called intercalation, anchoring tightly at guanine-cytosine sites. This distorts the DNA template.
Step 3: With the antibiotic lodged in the helix, RNA polymerase can no longer read the DNA, so the making of RNA from a DNA template (transcription) is shut down. Thus actinomycin D inhibits DNA-dependent RNA synthesis.
Step 4: It neither stimulates transcription nor touches the RNA-to-DNA reverse transcription pathway, ruling out the other three options.
\[\boxed{Inhibits\ DNA\ dependent\ RNA\ synthesis}\]
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