mitosis sorts DNA equally into two separate nuclei 1 Prophase and Prometaphase cell prepares to sort the chromosomes 2 Metaphase chromosomes are moved to the center of the cell 3 Anaphase chromosomes are sorted 4 Telophase the new nuclei are formed Then each new cell gets one of these nuclei during cytokinesis Interphase duplicates DNA centrosomes used to identify poles of the cell during division process are formed cell replicates DNA resulting in two sister chromatids attached by centromere Prophase DNA condenses into chromosomes making them easier to sort this inhibits protein synthesis nucleoli disappear and nuclear envelope disintegrates centrioles originate to help sort and organize chromatids microtubules disassembled from cytoplasm and reassembled into mitotic spindle Prometaphase nuclear envelope is fully broken down allowing microtubules to attach to centromeres chromosome form two kinetochores proteins on the centromere at centromere microtubules attach to the chromosomes Metaphase chromosomes align in middle of the cell Anaphase kinetochore proteins break down microtubules individual chromosomes move to opposite poles of the cells by the end each pole of the cell contains identical set of chromosomes Telophase nuclei at each pole form again chromosomes are now separated into two identical nuclei Cytokinesis separation of the cytoplasm into two new daughter cells tumor suppressor genes important proto oncogenes genes that encourage cell division mutations can cause these to stop working properly mutagens chemicals in the environment that produce mutations carcinogens mutagens that have shown that they can cause cancer i e cigarettes development of cancer requires mutations in both proto oncogenes and tumor suppressant genes oncogene malfunctioning proto oncogene because it promotes development of cancer Asexual reproduction all genes are passed onto daughter cells efficient and fast less genetic variability v sexual reproduction in optimal conditions this is favorable Sexual reproduction two parents combined enables offspring to deal with environmental changes better 23 pairs of chromosomes 22 are autosomes 1 is sex chromosomes X Y haploid gametes produced during meiosis fuse to form a diploid zygote each set of homologues have same genes one homologue comes from mom and one from dad chromosomes in parent cell are divided in half because homologous chromosomes are separated one homologue with sister chromatid go to one daughter cell the other goes to other Meiosis I reduction division somatic cells Meiosis II same as I except half as many chromosomes sister chromatids are separated from each other starts with two haploid cells containing too much DNA sister chromatids separate from each other produce 4 haploid cells not all always viable germ cells crossing over process in which genes swap position on matching chromosomes resulting in new combo of genes on each chromosome happens in I metaphase I homologous pairs of chromosomes line up on metaphase plate anaphase I homologous pairs are pulled apart and they move toward poles of cell telophase I cytokinesis occurs and 2 new daughter cells formed