Which list correctly names the four nitrogenous bases that make up the genetic code in a DNA molecule?

Introduction / Context:
DNA (deoxyribonucleic acid) stores genetic information using four nitrogenous bases. This question tests your knowledge of the correct set of bases found in DNA. Knowing these bases is essential for understanding base pairing, replication, transcription, and the genetic code.

Given Data / Assumptions:
• DNA uses a specific set of four bases. • RNA uses a slightly different set, replacing one base. • Only one option lists all four DNA bases correctly and includes no extras.

Concept / Approach:
The four bases in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G). In RNA, thymine is replaced by uracil (U). Therefore, any list that includes uracil is not a correct list of DNA bases. To answer the question, look for an option that includes adenine, thymine, cytosine, and guanine, and does not include uracil or any other base.

Step-by-Step Solution:
Step 1: Recall the four bases used in DNA: A, T, C, G. Step 2: Check each option for the presence of these four bases. Step 3: Identify any option that includes uracil (U), which belongs to RNA, not DNA. Step 4: See that option A lists adenine, thymine, cytosine, and guanine and does not include uracil. Step 5: Confirm that none of the other options list exactly these four bases without uracil.

Verification / Alternative check:
Textbooks often highlight the pairing rules: adenine pairs with thymine (A T), and cytosine pairs with guanine (C G) in DNA. Since these are the only bases in DNA, any complete list of DNA bases must include these four. RNA pairing is slightly different and uses adenine, uracil, cytosine, and guanine, reinforcing that uracil is excluded from DNA. This confirms that the correct list is adenine, thymine, cytosine, and guanine.

Why Other Options Are Wrong:
Option B: Includes uracil, which is not found in DNA, and omits guanine. Option C: Also includes uracil instead of thymine, so it is an RNA like set, not DNA. Option D: Contains uracil and lacks cytosine, so it is not the full DNA base set. Option E: Includes uracil and leaves out adenine, so it is incorrect for DNA.

Common Pitfalls:
A common mistake is to forget which nucleic acid uses uracil and which uses thymine. Some students also think that RNA and DNA share all bases, which is not correct. To avoid confusion, always associate thymine with DNA and uracil with RNA. Another pitfall is failing to check that the list includes all four DNA bases and no extras; make sure every required base is present.

Final Answer:
The four nitrogenous bases that make up DNA are adenine, thymine, cytosine, and guanine.