Which one is correct?

Options

A. Adenine = Pyrimidine, Uracil = Purine
B. Adenine = Purine, Uracil = Purine
C. Adenine = Adeniylic acid: Uracil = Uridylic acid
D. Adenine = Purine, Uracil = Pyrimidine

Answer

To determine which statement is correct regarding uracil and pyrimidines, let's analyze the options provided in the video transcript step by step.

### Step 1: Understand the Definitions
- **Pyrimidines**: These are one of the two classes of nitrogenous bases found in nucleic acids. The pyrimidines include cytosine (C), thymine (T), and uracil (U).
- **Uracil**: This is a specific type of pyrimidine that is found in RNA. It replaces thymine, which is found in DNA.

### Step 2: Analyze Each Option
1. **1st option**: "pyrimidine and uracil is pyrimidine" - This is correct because uracil is indeed a type of pyrimidine.
2. **2nd option**: "pyrimidine and uracil is pyrimidine" - This is also correct for the same reason as the first option.
3. **3rd option**: "uracil and uracil is pyrimidine" - This is correct because it states that uracil is a pyrimidine.
4. **4th option**: "pyrimidine and uracil is pyrimidine" - This is again correct, similar to the first and second options.

### Step 3: Identify the Correct Statement
All options provided in the transcript affirm that uracil is a pyrimidine. However, the question asks which one is correct, implying there is a singular correct answer. Since all options are correct, we can conclude that any of the options that state uracil is a pyrimidine are valid.

### Conclusion
The correct statements are:
- "uracil is pyrimidine" (as stated in the 3rd option) and
- "uracil is a type of pyrimidine" (as stated in the 1st, 2nd, and 4th options).

### Final Answer
All options correctly state that uracil is a pyrimidine.

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