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DNA consists of long chains of nucleotides, each containing one of four nitrogenous bases: adenine (A), thymine (T), guanine (G), and cytosine (C). These bases pair up in a specific manner to form the distinctive double-helix structure of DNA. It is vital to understand the base pairing rules because they ensure that DNA replicates correctly during cell division. This process allows genetic information to be accurately passed from one generation to the next.

Base pairing is based on hydrogen bonds forming between the bases, which ensures that the DNA strands stay bonded securely. The specificity of these pairings underpins the molecule's information storage capacity, helping it maintain the integrity of genetic codes.

In the context of DNA, nucleotide percentages refer to the proportion of each of the four bases (A, T, G, C) within a DNA molecule. Since DNA is composed of two complementary strands, the percentages are key to understanding its composition. When given the GC content of a DNA molecule, you can easily deduce the percentages of the G and C nucleotides.

Simply put, if the GC content is provided as, say, 48%, this implies that guanine and cytosine together make up 48% of the DNA. Their individual contributions will each be half of this, i.e., 24% each. Through the knowledge of nucleotide pairings, we can also calculate the percentages of adenine and thymine, by subtracting the GC content from 100% and dividing the result evenly between A and T.

Adenine always pairs with thymine, forming one of the crucial complementary pairs in the DNA structure. This pairing is stabilized by two hydrogen bonds, which, although weaker than the three hydrogen bonds found in GC pairing, ensures proper DNA replication and function.

In any given strand of DNA, the amount of adenine will exactly match the amount of thymine. This equimolecular ratio allows one to infer their percentage if the other percentages (such as GC content) are known. For example, if the GC content accounts for a certain percentage, the AT content can be determined by subtracting the GC percentage from the total 100%.

Guanine pairs with cytosine, forming a pairing that is essential to the double-helix structure of DNA. This pairing is bonded by three hydrogen bonds, making them more stable than AT pairs. This increased stability is significant because regions of DNA with a high GC content are often more thermally stable and partake in critical roles in genome stability.

Just like AT pairing, the percentage of guanine in a DNA molecule is equal to the percentage of cytosine. In a scenario where the GC content is given, this percentage accounts for the total combined presence of guanine and cytosine. Understanding these pairings not only aids in determining nucleotide percentages but also gives insights into the physical characteristics of DNA and its functional aspects during cellular processes.