GRE Subject Test: Chemistry : Nucleic Acids

Study concepts, example questions & explanations for GRE Subject Test: Chemistry

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Example Questions

Example Question #4 : Structure Of Dna And Rna

Of the following groups of nitrogenous bases, which does not contain a purine?

Possible Answers:

Thymine, adenine, cytosine

Cytosine, thymine, uracil

Adenine, guanine, thymine

Guanine, uracil, adenine

Cytosine, thymine, guanine

Correct answer:

Cytosine, thymine, uracil

Explanation:

We can use the mnemonic "PurAG" to remember that the purines are adenine and guanine. The only choice that does not contain a purine, therefore, is "cytosine, thymine, and uracil." Remember, pyrimidines contain a single ring, while purines have two.

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