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According to Chargaff's rule, base pairing in DNA should resemble which of the following?

A. [tex]A=T ; C=G[/tex]
B. [tex]A=C ; T=G[/tex]
C. [tex]A=G ; T=U[/tex]
D. [tex]A=U ; C=G[/tex]


Sagot :

To determine the correct base pairing in DNA according to Chargaff's rule, we need to understand the fundamental principles of how bases pair in DNA.

Chargaff's Rule states that in DNA:
- The amount of adenine (A) is equal to the amount of thymine (T).
- The amount of cytosine (C) is equal to the amount of guanine (G).

Let's evaluate each of the given options based on this rule:

1. Option 1: [tex]$A = T ; C = G$[/tex]
- This option states that adenine pairs with thymine, and cytosine pairs with guanine.
- This correctly follows Chargaff's rule.

2. Option 2: [tex]$A = C ; T = G$[/tex]
- This option states that adenine pairs with cytosine, and thymine pairs with guanine.
- This does not follow Chargaff’s rule, as it mismatches the pairs.

3. Option 3: [tex]$A = G ; T = U$[/tex]
- This option states that adenine pairs with guanine, and thymine pairs with uracil.
- This also does not follow Chargaff’s rule, and uracil (U) is found in RNA, not in DNA.

4. Option 4: [tex]$A = U ; C = G$[/tex]
- This option states that adenine pairs with uracil, and cytosine pairs with guanine.
- Again, this does not follow Chargaff’s rule, and uracil is applicable to RNA rather than DNA.

Conclusion:
Chargaff's rule accurately applies to DNA where adenine (A) pairs with thymine (T) and cytosine (C) pairs with guanine (G). Based on this knowledge, the correct answer is

[tex]\[ \boxed{A = T ; C = G} \][/tex]

Therefore, the correct option is Option 1.