if A=120 and C120, then a piece of DNA will have ______nucleotides.

Options

A. 240
B. 280
C. 480
D. Data insufficient

Explanation

To solve the question, "If A = 120 and C = 120, then a piece of DNA will have ______ nucleotides," we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Components of DNA:**
- DNA is made up of nucleotides, which consist of a nitrogenous base, a sugar molecule, and a phosphate group.
- The nitrogenous bases in DNA are adenine (A), thymine (T), cytosine (C), and guanine (G).

2. **Base Pairing Rules:**
- In DNA, adenine pairs with thymine (A-T) and cytosine pairs with guanine (C-G).
- According to Chargaff's rules, the amount of adenine is equal to thymine (A = T), and the amount of guanine is equal to cytosine (G = C).

3. **Given Values:**
- The problem states that A = 120 and C = 120.
- Therefore, based on the base pairing rules:
- Since A = 120, T must also equal 120 (A = T).
- Since C = 120, G must also equal 120 (C = G).

4. **Calculating Total Nucleotides:**
- Now we can calculate the total number of nucleotides in the DNA strand.
- The total number of nucleotides is the sum of all the bases:
- Total nucleotides = A + T + C + G
- Substituting the values we have:
- Total nucleotides = 120 (A) + 120 (T) + 120 (C) + 120 (G)
- Total nucleotides = 120 + 120 + 120 + 120 = 480.

5. **Final Answer:**
- Therefore, the piece of DNA will have **480 nucleotides**.