<span>The structure of a paramecium that holds a "reserve copy" of all the cell's genes is the micro nucleus. </span>The micro nucelus is one of the <span>two kinds of </span>nuclei the paramecium has. The other is the<span> large ellipsoidal </span>nucleus<span> called a macronucleus. Every paramecium must have at least one small </span>nucleus<span> called a </span>micronucleus. The micronucleus is a storage site for the germline genetic material of the organism.