Q. 48 Which of the statements is TRUE for transposable elements 𝑨𝒄 and 𝑫𝒔 ?
(A) Both 𝐴𝑐 and 𝐷𝑠 are autonomous because they encode their own transposase
(B) Both 𝐴𝑐 and 𝐷𝑠 are non-autonomous because they do not encode their own transposase
(C) Only 𝐴𝑐 is autonomous because it encodes its own transposase
(D) Only 𝐷𝑠 is autonomous because it encodes its own transposase
Ac and Ds Transposable Elements: Which Statement is True?
Ac and Ds elements are key transposable elements in maize genetics, discovered by Barbara McClintock, where Ac is autonomous and Ds relies on it for movement. The correct answer to this question is option (C): Only Ac is autonomous because it encodes its own transposase.
Correct Answer
Option (C) states that only Ac is autonomous because it encodes its own transposase. Ac contains a 3.5 kb open reading frame producing an 807-amino-acid transposase enzyme, enabling independent transposition. Ds lacks this coding sequence and transposes only when Ac provides the enzyme.
Option Analysis
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(A) Both Ac and Ds are autonomous because they encode their own transposase: Incorrect, as Ds cannot produce transposase and depends on Ac.
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(B) Both Ac and Ds are non-autonomous because they do not encode their own transposase: Wrong, since Ac is fully autonomous with its own transposase gene.
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(C) Only Ac is autonomous because it encodes its own transposase: Correct for the reasons above.
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(D) Only Ds is autonomous because it encodes its own transposase: False, as Ds is non-autonomous by definition.
