题目
题目
单项选择题

Two distinct classes of aminoacyl-tRNA synthetases exist. What might explain this? Please choose the correct answer from the following choices,

选项
A.One class contains modified amino acids that specifically bind the modified bases of some tRNAs.
B.Recognition sites on both faces of tRNA may be required to distinguish 20 different tRNAs.
C.Two classes are needed because tRNAs can be both L-shaped or cloverleaf shaped.
D.One class of aminoacyl-tRNA synthetases is used for hydrophobic amino acids while the other class is used for the polar amino acids.
E.None of the above
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思路分析
Topic context: the question asks why there are two distinct classes of aminoacyl-tRNA synthetases. Each option is evaluated for its plausibility in explaining this division. Option 1: 'One class contains modified amino acids that specifically bind the modified bases of some tRNAs.' This is not a standard explanation for the existence of two synthetase classes; the division is not generally attributed to modified amino acids within tRNAs, but rather to recognition mechanisms and structural differences in tRNA. Therefore this statement is unlikely to be the reason for having two classes. Op......Login to view full explanation

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