GEN-3020 Lecture 3: CHP 2 (Meiosis & Fertilization)
Document Summary
Most diversity of life is a result of sexual reproduction: meiosis - the process in which chromosome number of a eukaryotic cell divide to give rise to haploid reproductive cells. There are two inner processes that total two divisions: fertilization - the process of developing gametes from the products of spermatogenesis and oogenesis. Meiosis i and ii each have a prophase, metaphase, anaphase, and telophase stage. Meiosis i carries out a reduction division where the diploid number of chromosomes are reduced to haploid. Meiosis ii represents the equal division of the remaining chromosomes. Leptonema, chromosomes appear as long single threads, unassociated with each other. Chromomeres, ( idiomeres ) serially aligned beads or ganules, are present at this point. Zygonema, two homologous chromosomes are paired in a process called synapsis. Each pair of homologous chromosomes is called bivalent. Pachynema, bivalents become shorter and split into two sister chromatids called tetrads.