karyogámiát

Karyogamy is a crucial stage in sexual reproduction in eukaryotic organisms. It refers to the fusion of two haploid nuclei, typically from gametes, to form a single diploid nucleus. This process is the culmination of fertilization and leads to the restoration of the diploid chromosome number characteristic of the species.

In many fungi and algae, karyogamy occurs as a distinct event after plasmogamy, the fusion of the cytoplasm of two parent cells. This results in a dikaryotic stage where each cell contains two separate haploid nuclei. Eventually, these nuclei fuse to form a diploid zygote nucleus. In animals and some other eukaryotes, karyogamy is often more directly coupled with plasmogamy. The sperm nucleus enters the egg, and their nuclei fuse shortly thereafter, forming the zygote nucleus.

The diploid nucleus formed by karyogamy contains a complete set of chromosomes, with one set inherited from each parent. This genetic recombination is a fundamental source of genetic variation within a population. Following karyogamy, the diploid nucleus typically undergoes meiosis to produce haploid spores or gametes, thus completing the sexual reproductive cycle. The timing and specific mechanisms of karyogamy can vary significantly among different organisms, reflecting the diversity of life.