MEIOSIS II
Prophase II:• While chromosome duplication took place prior to meiosis I, no new chromosome replication occurs before meiosis II.
• The centrioles duplicate. This occurs by separation of the two members of the pair, and then the formation of a daughter centriole perpendicular to each original centriole. The two pairs of centrioles separate into two centrosomes.
• The nuclear envelope breaks down, and the spindle apparatus forms.
• The centrioles duplicate. This occurs by separation of the two members of the pair, and then the formation of a daughter centriole perpendicular to each original centriole. The two pairs of centrioles separate into two centrosomes.
• The nuclear envelope breaks down, and the spindle apparatus forms.
Metaphase II:• Each of the daughter cells completes the formation of a spindle apparatus.
• Single chromosomes align on the metaphase plate, much as chromosomes do in mitosis. This is in contrast to metaphase I, in which homologous pairs of chromosomes align on the metaphase plate.
• For each chromosome, the kinetochores of the sister chromatids face the opposite poles, and each is attached to a kinetochore microtubule coming from that pole.
• Single chromosomes align on the metaphase plate, much as chromosomes do in mitosis. This is in contrast to metaphase I, in which homologous pairs of chromosomes align on the metaphase plate.
• For each chromosome, the kinetochores of the sister chromatids face the opposite poles, and each is attached to a kinetochore microtubule coming from that pole.
Anaphase II:• The centromeres separate, and the two chromatids of each chromosome move to opposite poles on the spindle. The separated chromatids are now called chromosomes in their own right.
Telophase II:• A nuclear envelope forms around each set of chromosomes.
• Cytokinesis takes place, producing four daughter cells (gametes, in animals), each with a haploid set of chromosomes.
• Because of crossing-over, some chromosomes are seen to have recombined segments of the original parental chromosomes.
• Cytokinesis takes place, producing four daughter cells (gametes, in animals), each with a haploid set of chromosomes.
• Because of crossing-over, some chromosomes are seen to have recombined segments of the original parental chromosomes.