4 Truths Hidden Inside the Molecules That Make You

Living systems grow, sustain, and reproduce themselves. The most strange fact about a living system is that it is composed of non-living atoms and molecules. We are, essentially, organized collections of chemistry obeying standard laws.

Biochemistry is the field that studies this chemistry. It reveals that the building blocks of life often follow rules that defy simple intuition. Sugars and proteins hide elegant complexities. Here are four specific details that clarify the nature of biomolecules.

1. Carbohydrates Aren’t Just “Hydrated Carbon”

The name “carbohydrate” originated from the observation that many simple sugars fit the formula C_x(H₂O)_y. This suggested a structure of carbon atoms combined with water molecules. Glucose (C₆H₁₂O₆) fits this pattern perfectly.

This rule fails upon closer inspection. Acetic acid (CH₃COOH) fits the formula but is not a carbohydrate. Rhamnose (C₆H₁₂O₅) is a carbohydrate but does not fit the formula.

2. The “Inverting” Trick of Sucrose

Sucrose (table sugar) is dextrorotatory, meaning it rotates polarized light to the right. When hydrolyzed, it splits into glucose and fructose. The resulting mixture behaves differently. Glucose rotates light to the right (+52.5°), but fructose rotates light strongly to the left (–92.4°). The strong leftward rotation of fructose overpowers the glucose. The mixture becomes laevorotatory. This specific mixture is called Invert Sugar.

3. Cooking Only Changes Shape, Not Sequence

When you boil an egg, the white coagulates. This is denaturation. Heat disturbs the hydrogen bonds holding the protein chains in their specific 3D shape (globules and helices). The chains unfold. The biological activity is lost, but the chemical identity remains. The primary structure—the sequence of amino acids—remains intact. The blueprint survives the destruction of the building.

4. “Vitamin” is a Historical Typo

The term began as “Vitamine” (Vital + Amine) because early researchers thought all these compounds contained amino groups. Later research proved this false. The ‘e’ was dropped, leaving us with “Vitamin.” The name is a fossil of early scientific understanding.