A bioinformatician analyzing genetic sequences finds that the ratio of adenine (A) to thymine (T) bases in a DNA sample is $5:3$. If there are 15 adenine bases, how many thymine bases are there?

Tue, 05 May 2026 06:06:35 +0000

How DNA Analysis Reveals Genetic Ratios: Solving the A:T Base Comparison Understanding the composition of DNA is fundamental in bioinformatics, especially when analyzing genetic sequences. One key aspect is determining the ratio of nucleotide bases—specifically adenine (A) to thymine (T). In double-stranded DNA, base pairing ensures that adenine pairs with thymine in a consistent 1:1 ratio under normal conditions. However, researchers sometimes use ratio analysis to detect anomalies or validate sample integrity. Consider a recent bioinformatician study where genetic sequence data reveals that the ratio of adenine (A) to thymine (T) bases is $5:3$. This deviation from the expected 1:1 ratio may indicate sequencing artifacts, sample contamination, or biological variation. In this scenario, the researcher notes there are 15 adenine (A) bases in a DNA sample. Using the ratio, we can determine the exact number of thymine (T) bases present. Let the number of thymine bases be $x$. Given the ratio $A:T = 5:3$, and knowing $A = 15$, we set up the proportion: