Which of the following equations are true for the percentages of nucleotides in double-stranded DNA?
(A)/(C)=(G)/(T)

Verified step by step guidance

1. Understand the structure of double-stranded DNA: DNA is composed of two complementary strands, where adenine (A) pairs with thymine (T) and cytosine (C) pairs with guanine (G). This pairing is governed by Chargaff's rules.
2. Recall Chargaff's rules: In double-stranded DNA, 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). Mathematically, this can be expressed as: $A=T$ and $C=G$.
3. Analyze the given equation: The equation provided is $\frac{A}{C}=\frac{G}{T}$. To determine if this equation is true, consider the relationships between the nucleotide pairs.
4. Apply Chargaff's rules to the equation: Since $A=T$ and $C=G$, the ratios $\frac{A}{C}$ and $\frac{G}{T}$ are not necessarily equal because the numerator and denominator in each fraction represent different nucleotide pairs.
5. Conclude based on the analysis: The equation $\frac{A}{C}=\frac{G}{T}$ does not align with Chargaff's rules, as the ratios of different nucleotide pairs are not inherently equal in double-stranded DNA.

Key Concepts

Chargaff's Rules

Chargaff's Rules state that in double-stranded DNA, the amount of adenine (A) is equal to thymine (T), and the amount of cytosine (C) is equal to guanine (G). This means that A pairs with T and C pairs with G, leading to the conclusion that the ratios of these nucleotides are equal in a double helix structure.

Base Pairing

Base pairing refers to the specific hydrogen bonding between nucleotides in DNA. Adenine pairs with thymine through two hydrogen bonds, while cytosine pairs with guanine through three hydrogen bonds. This complementary pairing is crucial for the stability of the DNA structure and for accurate DNA replication.

Nucleotide Composition

The nucleotide composition of DNA refers to the relative amounts of the four nucleotides: adenine, thymine, cytosine, and guanine. In double-stranded DNA, the total percentage of A and T will equal the total percentage of C and G, which is essential for understanding the relationships and ratios among these nucleotides in the context of the question.