What holds atoms in compounds together?

Glycogen is an energy-storage molecule in humans. a hormone that is called insulin controls the storage of glycogen in the liver. insulin is made up of amino acids.

Zoo geographic regions are characterized by the presence of specific groups of animals these regions are determined by the taxonomic or phylogenetic relationships of animals. the map shows the zoogeographic regions proposed by the naturalist alfred russel wallace in 1876. the similarities of organisms in which two areas numbered above provide the best evidence for common ancestry between the organisms in both locations ?

Which macromolecule catalyzes chemical reactions this be considered enzyme chemical reactions thus he considering enzymes