meiosis vs mitosis

• cells in reproductive organs divide by meiosis, which forms gametes
• gametes have half the number chromosomes ( 23 ) - they are haploid cells
• meiosis

  1. chromosomes are doubled and lines up in the centre of the cell
  2. cell divides
  3. cell divides again, 2 divisions (has 23 chromosomes) -> formed gametes that are genetically different
• meiosis is the formation of 4 genetically different haploid daughter cells from one parent cell
• gametes fuse at fertilisation and produces a diploid cell with 46 chromosomes
• mitosis is the division which results in two genetically identical diploid daughter cells
• mitosis is required for:

  • growth
  • repair
  • asexual reproduction
• what are the steps for mitosis:

  • interphase
  • prophase
  • metaphase
  • anaphase
  • telophase
  • cytokenisis
• what is interphase : preparation for mitosis
• mitosis:

  1. interphase -> prep for cell division: DNA is duplicated and cell-structures are also copied
  2. prophase -> nuclear membranes break down and spindle fibres are formed
  3. metaphase -> chromosomes are lined up in the centre of the cell and attracted to spindle fibres
  4. anaphase -> chromosomes are pulled apart and chromatids are pulled to opposite ends of the cell
  5. telophase -> nuclear membrane starts to reform around the chromosomes that are at either end
  6. cytokenisis -> cytoplasm and cell membrane divides to form two seperate cells
• tumours usually form as a result of uncontrolled cell division, which can lead to cancer