Question

Purines found both in DNA and RNA are:

• A. Adenine and thymine
• B. Adenine and guanine
• C. Guanine and cytosine
• D. Cytosine and thymine

Answer 1

The Correct Option is B

To determine which purines are found in both DNA and RNA, we need to understand the structure of nucleic acids and their components.

Purinic Bases:

• In nucleic acids, purines form one of the two categories of nitrogenous bases. Purines possess a two-ring structure.
• The purines present in both DNA and RNA are Adenine (A) and Guanine (G).

Pyrimidines:

• Pyrimidines, which are the other category of nitrogenous bases, have a single-ring structure.
• The pyrimidines in DNA are Thymine (T) and Cytosine (C), whereas in RNA, they are Uracil (U) and Cytosine (C).

Here's why each option is valid or not:

1. Adenine and thymine: Thymine is a pyrimidine base found only in DNA.
2. Adenine and guanine: Both are purines and are present in both DNA and RNA. This is the correct answer.
3. Guanine and cytosine: Cytosine is a pyrimidine, not a purine.
4. Cytosine and thymine: Both are pyrimidines, not purines.

Therefore, the purines found in both DNA and RNA are indeed Adenine and Guanine, which corresponds to option Adenine and guanine.