Certainly! Let's break down the question step by step.
1. Understanding Chargaff's Rule:
- Chargaff's rule is a key principle in molecular biology that helps us understand the pairing of nucleotide bases in DNA.
- According to this rule, the amount of adenine (A) is equal to the amount of thymine (T) and the amount of cytosine (C) is equal to the amount of guanine (G).
2. Base Pairing in DNA:
- DNA is made up of four types of nucleotide bases: adenine (A), thymine (T), cytosine (C), and guanine (G).
- Based on Chargaff's rule, in a DNA molecule:
- Adenine (A) pairs with Thymine (T)
- Cytosine (C) pairs with Guanine (G)
3. Analyzing the Options:
- Let's evaluate each option given in the question:
1. [tex]\( A = T ; C = G \)[/tex]: This option states that adenine pairs with thymine and cytosine pairs with guanine, which aligns perfectly with Chargaff's rule.
2. [tex]\( A = C ; T = G \)[/tex]: This option incorrectly pairs adenine with cytosine and thymine with guanine, which does not match Chargaff's rule.
3. [tex]\( A = G ; T = U \)[/tex]: This option incorrectly pairs adenine with guanine and thymine with uracil. Additionally, uracil (U) is not found in DNA but in RNA, making this statement incorrect for DNA.
4. [tex]\( A = U ; C = G \)[/tex]: This option pairs adenine with uracil and cytosine with guanine. While cytosine pairing with guanine is correct, adenine should pair with thymine in DNA, not uracil, which again is found in RNA.
4. Concluding the Answer:
- Based on the correct understanding of Chargaff's rule, the option that correctly states the base pairing is:
[tex]\( A = T ; C = G \)[/tex]
Thus, the correct answer is [tex]\( A = T ; C = G \)[/tex].
