Question

Chargaff's rule states that in an organism

• A. amount of adenine (A) is equal to that of cytosine (C) and the amount of thymine (T) is equal to that of guanine (G)
• B. amounts of all bases are equal
• C. amount of adenine (A) is equal to that of thymine (T) and the amount of guanine (G) is equal to that of cytosine (C)
• D. amount of adenine (A) is equal to that of guanine (G) and the amount of thymine (T) is equal to that of cytosine (C)

Answer 1

The Correct Option is C

To solve this question, we need to understand Chargaff's rule. Chargaff's rule is a guideline for the base pairing in DNA.

• DNA is composed of four nucleotides, each containing one of these bases: adenine (A), thymine (T), guanine (G), or cytosine (C).
• Chargaff's rule states that in any double-stranded DNA molecule, the number of adenine (A) bases is equal to the number of thymine (T) bases, and the number of guanine (G) bases is equal to the number of cytosine (C) bases.
• This occurs because of specific base-pairing: A pairs with T and G pairs with C.

Now, let's analyze the given options:

1. Amount of adenine (A) is equal to that of cytosine (C) and the amount of thymine (T) is equal to that of guanine (G): This statement is incorrect because it doesn't follow Chargaff's rule of base pairing.
2. Amounts of all bases are equal: This is incorrect as Chargaff's rule states the equality of specific pairs, not all four bases.
3. Amount of adenine (A) is equal to that of thymine (T) and the amount of guanine (G) is equal to that of cytosine (C): This is the correct statement according to Chargaff's rule.
4. Amount of adenine (A) is equal to that of guanine (G) and the amount of thymine (T) is equal to that of cytosine (C): This pairing is incorrect as it does not follow the known pairings in DNA.

Therefore, the correct answer is: amount of adenine (A) is equal to that of thymine (T) and the amount of guanine (G) is equal to that of cytosine (C).