Comparing amino acid sequences in proteins has been used to determine the relatedness of organisms. Below is a graphic that shows the amino acid sequence differences between different organisms for a protein keratin. Changes in amino acid sequences are known to cause changes in structure of proteins.

Glucose, also called grape sugar, blood sugar or corn sugar, is among the simplest and one of the primary naturally occurring sugars. produced naturally by plants as the primary photosynthesis product, it is heavily used by living beings as a main energy source and is necessary for cellular respiration. chemically, it is a monosaccharide carbohydrate and serves as a building block for complex sugars like starch.