Final answer:
In Paramecium, the migratory pronucleus is transferred between conjugating cells during sexual reproduction, while the stationary pronucleus remains in the cell to fuse with the incoming migratory pronucleus, resulting in genetic exchange. The macronucleus disintegrates and a new one is formed from the micronucleus after this process, ensuring genetic renewal.
Step-by-step explanation:
The characteristics of the migratory and stationary pronuclei in Paramecium are integral to its sexual reproduction process, named conjugation. During this process, the migratory pronucleus is the haploid nucleus which translocates from one cell to the partner cell after both cells have exchanged micronuclei during conjugation. The stationary pronucleus is the haploid nucleus that remains in the cell and fuses with the migratory pronucleus of the other cell to form a new organism with a novel genetic makeup. The macronucleus, involved in asexual reproduction, eventually disintegrates and a new macronucleus is formed from the micronucleus after a series of nuclear divisions and DNA processing.
The macronucleus, although it directs asexual binary fission and other biological functions, is not involved directly in the process of conjugation—instead, it is replaced by a new macronucleus derived from the newly formed diploid micronucleus. The micronucleus, which is critical for sexual reproduction, undergoes meiosis, followed by mitosis, to contribute to the genetic exchange and variability seen in Paramecium reproduction, a key aspect of their survival and evolution.