Researchers in the field of biotechnology are finding exact chemical preferences of stem cells, designing synthetic three dimensional locations for them, and learning the differentiation of an embroyonic stem cell into specific cell types using small molecules. Chemists are also discovering new small molecules that achieve a form of cellular alchemy: the reprogramming of normal cells into stem cells. In embryonic stem cells, the genes that code for proteins in the self-renewal and differentiation pathways are marked by a pattern of methylation and acetylation on the histone proteins around which genomic DNA is wound. Biochemists are also studying small molecules that can be placed in media for self-renewal of embryonic stem cells and differentiate them with adult cells. The researchers are using synthetic polymers such as polyacrylamide, copolymerized with a polyethylene glycol tipped with peptides, for understanding the stem cells.