Science 8 Cell division

• Genetics is the study of heredity and variation
• Chromosome


  A single molecule of DNA tightly coiled many times around proteins
• Humans have 23 pairs of chromosomes
• Centromere


  The constriction point of a chromosome that gives it its shape and the location of genes
• Cell cycle


  Growth and development between a cell's birth and reproduction to make two new daughter cells
• Cell cycle stages


  • Interphase (G1, S, G2)
  • Cell division (Mitosis or Meiosis)
• Interphase


  The first stage of the cell cycle where the cell grows, replicates DNA, and prepares for cell division
• Mitosis


  Cell division that produces two identical daughter cells with the same number of chromosomes
• Meiosis


  Cell division that produces four daughter cells with half the number of chromosomes
• Stages of mitosis


  • Prophase
  • Metaphase
  • Anaphase
  • Telophase
• Stages of meiosis


  • Prophase I
  • Metaphase I
  • Anaphase I
  • Telophase I
  • Prophase II
  • Metaphase II
  • Anaphase II
  • Telophase II
• Meiosis is a special type of cell division that reduces the chromosome number by half
• Meiosis produces gametes (sperm and egg cells) with half the normal chromosome number
• Mitosis produces two genetically identical daughter cells
• Meiosis produces four genetically distinct daughter cells
• Mitosis


  Produces two identical cells with the same number of chromosomes
• Meiosis


  Produces cells with half the normal chromosome number
• First Gap Period This stage is characterized by protein and Ribonucleic acid (RNA) synthesis. RNA, which is synthesized based on the DNA, is then used to synthesize proteins.
• G2 represents a phase where cell rapidly grows and also prepare for cell division.
• The Cell Cycle Synthesis stage The chromosomes are duplicated in preparation for the next cell division "Middle Stage"