So remember that a primer molecule is basically a short sequence of glucose nucleotides which are connected by alpha one four glycocytic bonds. So why do we need a primer molecule? Because the enzyme that elongates that glycogen chain, known as glycogen synthase, needs a primer to actually initiate that elongation process. It simply cannot begin from scratch. And the enzyme that generates that primer is known as glycogenin. So it is not shown in the diagram, but basically an enzyme known as glycogenin creates this primer.