Unity and Diversity A.2 Nucleic Acids (id: 68f2e3304)

本题目来源于试卷: Unity and Diversity A.2 Nucleic Acids，类别为 IB生物学

[单选题]
Which of the labelled s5. +8mhasdqod w ,pawhq;v .*itructures shows the correct directionality of the DNA molecv,*h;wa.pqw i ule?

A.
B.
C.
D.


参考答案:  C


本题详细解析:
Choice C is correct because the left strand is ra2favih+ w sh*h;w--m unning in the 5’ - 3’ direction with the phosphate group attached to the 5th carbon at the 5’ end, and the 3rd carbon of the terminating deoxyribose sugar is free. The right strand is running antiparallel in the 3’-5’ direction.Ch2;i hafh*v+-ms wa-w hoice A is incorrect because both strands are labelled as running in the 5’ - 3’ direction, and the carbons of the deoxyribose sugars are incorrectly labelled. Choice B is incorrect because the strands are incorrectly labelled with the 5’ and 3’ ends, and the carbons of the deoxyribose sugars are incorrectly labelled on both strands. Choice D is incorrect because both strands are labelled as running in the 3’ - 5’ direction, and the carbons of the deoxyribose sugars on both strands are incorrectly labelled.

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