THE MOLECULAR BASIS OF INHERITANCE
DNA REPLICATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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guanine because it’s a purine
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guanine because it’s a pyrimidine
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cytosine because it’s a purine
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cytosine because its a pyrimidine
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Detailed explanation-1: -The pyrimidines, cytosine and uracil, are smaller and have a single ring, while the purines, adenine and guanine, are larger and have two rings.
Detailed explanation-2: -The chemical structures of Thymine and Cytosine are smaller, while those of Adenine and Guanine are larger. Size and structure of the specific nucleotides cause Adenine and Thymine to always pair together while Cytosine and Guanine always pair together. Therefore the two strands of DNA are considered complimentary.
Detailed explanation-3: -The larger bases adenine and guanine are purines which differ in the kinds of atoms that are attached to their double ring. The other bases cytosine, uracil, and thymine are pyrimidines which differ in the atoms attached to their single ring.
Detailed explanation-4: -(A = adenine, etc). Notice also that there are two different sizes of base. Adenine and guanine are bigger because they both have two rings. Cytosine and thymine only have one ring each.
Detailed explanation-5: -Because of their structural similarity, we usually refer the nine-member double rings adenine and guanine as purines, and six-member single-ring thymine, uracil, and cytosine are pyrimidines.