Euchromatin represents uncoiled parts of chromosomes where many genes are being expressed. The chemical reactions on which life depends are mostly carried out within cells. These reactions can occur rapidly and specifically because each one is catalysed by a different O enzyme . Enzymes are made of proteins. Most of the structural components of cells are also proteins.
Ribosomes lie in the cytoplasm and are the sites where protein synthesis occurs.
Messenger RNA bears the coded instructions for the unique sequence of amino acids for a specific protein. Transfer RNA carries single amino acids to the ribosome for attachment to the growing polypeptide chain. Certain genes also code for useful RNA molecules, like the different transfer RNAs and ribosomal RNAs. There are multiple copies of the genes for rRNA and they are found on five different pairs of chromosomes. The nucleolus is the region of the nucleus where the parts of these chromosomes bearing the rRNA genes are concentrated.