In the context of DNA structure, which nitrogenous base is not found in DNA?

• A. Thymine
• B. Guanine
• C. Uracil
• D. Adenine

Answer: (C)

Verified step by step guidance

1. Recall the four nitrogenous bases that make up DNA: Adenine (A), Thymine (T), Guanine (G), and Cytosine (C).
2. Understand that DNA is a double-stranded molecule where Adenine pairs with Thymine, and Guanine pairs with Cytosine.
3. Recognize that Uracil (U) is a nitrogenous base found in RNA, not DNA.
4. Note that Uracil replaces Thymine in RNA, pairing with Adenine during RNA transcription.
5. Therefore, identify Uracil as the nitrogenous base not found in DNA.