mitosis and meiosis

• Asexual Reproduction


  One of the ways an organism can reproduce
• Mitosis


  One of the ways a cell can divide
• Asexual Reproduction Involving Mitosis


  1. An ordinary cell can make a new cell by dividing in two

  2. Both new cells are genetically identical to the original cell
• Mitosis


  Cell division where a cell reproduces itself by splitting to form two cells with identical sets of chromosomes
• Mitosis


  1. DNA forms X-shaped chromosomes

  2. Chromosomes line up in the centre of the cell

  3. Cell fibres pull the chromosomes apart

  4. Membranes form around each set of chromosomes

  5. Cell divides
• Mitosis is used for asexual reproduction, growth, and repair
• Sexual Reproduction


  Where genetic information from two organisms is combined to produce offspring which are genetically different to either parent
• Sexual Reproduction


  1. Parents produce gametes (sperm and egg cells)

  2. Gametes fuse to form a zygote (fertilised egg)

  3. Zygote undergoes cell division by mitosis to form an embryo

  4. Embryo inherits features from both parents
• Fertilisation of gametes is random, producing genetic variation in the offspring
• Meiosis


  A type of cell division that produces four haploid cells whose chromosomes are not identical
• Meiosis


  1. Cell duplicates its DNA

  2. Chromosomes line up in pairs in the centre of the cell

  3. Pairs of chromosomes are pulled apart, each new cell gets one copy of each chromosome

  4. Second division is like mitosis, resulting in four genetically different haploid gametes
• Meiosis only happens in the reproductive organs (ovaries and testes)