Chapter 2.2

• Unicellular organisms reproduce by mitosis
• Steps to Replication (Interphase):

  1. Strands of the DNA separate like a zip by DNA helicase
  2. The exposed nucleotides are paired up by free bases called DNA polymerase
  3. The result is 2 sets of DNA identical to the one at the beginning
  4. This is Interphase in Mitosis and Meiosis
• Multicellular organisms reproduce by meiosis
• Steps to Mitosis:

  1. Interphase: Chromosomes replicate to have 2 chromatids
  2. Prophase: Replicated chromosomes and their chromatids become visible
  3. Metaphase: The chromosomes line up on the equator of the cell. The spindle fibres appear from the ends of the chromosome.
  4. Anaphase: The spindle fibres contract. The chromatids separate and move to the ends of the cell.
  5. Telophase: 2 nuclei form, each with the same chromosomes as the mother cell
  6. Cytokinesis: The cell membranes form, making 2 daughter cells
• Mitosis produces two genetically identical daughter cells from one parent cell.
• Diploid cells have 46 chromosomes, 44 autosomes and 2 sex chromosomes.
• Haploid cells have half chromosomes and are called gametes
• Abnormal mitosis leads to cancers and tumors
• Mitosis produces diploid cells and is the method used for growth, repair and asexual reproduction
• In asexual reproduction, offspring are clones to their parents