Mitosis and Meiosis

Mitosis Cytokinesis Nuclear envelope start to disappear Chromosomes become visible Spindle fibers form from centrioles Each chromosome contains 2 sister chromatids DNA replicates Cell grows Chromosomes line up down middle of cell Spindle fibers attach to centromeres Nuclear envelope reforms Cell dimples Cell membrane/wall redevelops Gets ready for cytokinesis Chromosome split at centromere Pulled to centrioles Sister chromatids become chromsomes Cytokinesis Two daughter cells produced identical to one another

Meiosis 1 Prophase 1 Metaphase 1 Anaphase 1 Telophase 1 Homologous chromosomes pair up Tetrads form Crossing over can occur Prophase 1 Metaphase 1 Homologous chromosomes line up down middle of cell Spindle fibers attach to centromeres Anaphase 1 Homologous chromosomes split Telophase 1 Cell splits into 2 haploid cells

Meiosis 2 Telophase 2 Prophase 2 Metaphase 2 Anaphase 2 Two haploid cells Prophase 2 Chromosomes line up down middle of cell Spindle fibers attach to centromere Metaphase 2 Sister chromatids split at centromere Each become a chromosome Anaphase 2 Telophase 2 4 daughter cells are produced each containing 23 chromosomes (haploid) Carry identical genes but not identical traits

Comparison Mitosis Meiosis Results in 2 identical daughter cells Each containing 46 chromosomes Diploid Happens over vast majority of body Occurs so cell does not go into DNA overload Allows cell to be efficient Meiosis Results in 4 cells with the same “basic” genetic information Each cell contains 23 chromosomes Haploid Happens in reproductive organs Has Meiosis 1 and 2 Meiosis 1 has homologous chromosomes and tetrads