And that is about the maximum amount of energy we can expect from combustion of any molecule. 6H 2 O produces 16 kJ of energy or heat per gram of glucose. This is a ball and stick representation of glucose C 6 H 12 O 6 . Spheres are atoms, cylinders are bonds. The model has the advantage of showing the molecule in three dimensions.
Carbons are green, oxygens are red, hydrogens are silver.
When we eat proteins, these large molecules are often broken down into their amino acids and then reassembled to form other proteins. Protein Model - Insulin Ball and stick model of a representative protein, insulin. On thing we can see by inspection is that proteins are complex molecules containing significant oxygen and nitrogen. The third major energy source, fats, are composed of long hydrocarbon chains, similar to the many fuels we use in our lives such as gasoline, heating fuels, or candle waxes. This greater energy content of fats and saturated hydrocarbon fuels is due to the fact that these substances initially contain very little oxygen and can therefore combine with greater amounts of oxygen while they produce energy.