BIOL 102 Lecture Notes - Lecture 20: Asexual Reproduction, Chromosome, Zygote
Document Summary
The life cycles of almost all eukaryotic organisms have a common overall pattern. First, two haploid cells fuse during the process of fertilization, bringing together genes from different parental organisms and endowing the resulting diploid cell with new gene combinations. Second, at some point in the life cycle, meiotic cell division occurs, re-creating haploid cells. Third, at some time in the life cycle, mitotic cell division of either haploid or diploid cells, or both, results in the growth of multicellular bodies, or in asexual reproduction. In haploid life cycles, the majority of the cycle consists of haploid cells. Some eukaryotes, like fungi and unicellular algae, spend most of their life cycles in haploid state, with single copies of each type of chromosome. Asexual reproduction by mitotic cell division produces a population of identical, haploid cells. Under certain environmental conditions, specialized reproductive haploid cell are produced. Two of these reproductive cells fuse, forming a diploid zygote.
