Once a scientific idea is developed, it does not change. right?

amino acid

Explanation:

proteins are hetero polymers made up of number of monomers which are amino acids. an amino acid composed of 4 different groups in the structure. amino acids are linked by peptide bond in order to form a protein or polypeptide . in a structure of protein 20 different amino acids can be joined ..

monosaccharides are monomers of polysaccharides such as starch, glycogen, cellulose...

nucleotides are monomers of polynucleotide chains like DNA and RNA and also substances like ATP

fatty acids are monomers of lipids. fatty acids and glycerol reacts to form triglycerides which 're called lipids.

monomers are the building unit of a substance or polymer..

hope you get this correctly :)