Chargaff's rule is an important concept in molecular biology, and it states that in a DNA molecule, the number of adenine (A) bases is equal to the number of thymine (T) bases, and the number of cytosine (C) bases is equal to the number of guanine (G) bases. This is because adenine pairs with thymine and cytosine pairs with guanine due to hydrogen bonding.
Here are the options given:
1. [tex]\(A = T ; C = G\)[/tex]
2. [tex]\(A = C ; T = G\)[/tex]
3. [tex]\(A = G ; T = U\)[/tex]
4. [tex]\(A = U ; C = G\)[/tex]
Let's evaluate each option based on Chargaff's rule:
- [tex]\(A = T ; C = G\)[/tex]: This option correctly reflects Chargaff's rule. Adenine pairs with thymine, and cytosine pairs with guanine.
- [tex]\(A = C ; T = G\)[/tex]: This option does not follow Chargaff's rule. Adenine does not pair with cytosine, and thymine does not pair with guanine.
- [tex]\(A = G ; T = U\)[/tex]: This option is incorrect for several reasons. Adenine does not pair with guanine in DNA. Additionally, thymine (T) is present in DNA, but uracil (U) is found in RNA, not in DNA.
- [tex]\(A = U ; C = G\)[/tex]: This option is incorrect because uracil (U) is found in RNA, not DNA. In DNA, adenine pairs with thymine, not uracil.
Given these evaluations, the correct answer is:
[tex]\[ A = T ; C = G \][/tex]
This option correctly follows Chargaff's rule for base pairing in DNA.
