Cell division and cellular control

• Mitosis


  A form of cell division that produces identical cells, there are four stages: prophase, metaphase, anaphase and telophase
• Cell cycle


  1. Cell forms

  2. Cell grows

  3. Cell divides to form daughter cells
• Cell cycle


  • Controlled by checkpoints
• Cytokinesis


  1. Parent and replicated organelles move to opposite sides of the cell

  2. Cytoplasm divides to produce two daughter cells
• Interphase


  1. Cell grows

  2. Chromosomes and some organelles are replicated

  3. Chromosomes begin to condense
• Prophase


  1. Nuclear envelope breaks down and disappears

  2. Chromosomes condense

  3. Centrioles move to opposite poles for spindle formation
• Metaphase


  Chromosomes move to the equator and attach to spindle fibres via centromeres
• Anaphase


  Sister chromatids are separated
• Telophase


  1. Nuclear envelope reforms

  2. Spindle is broken down and disappears

  3. Chromosomes uncoil
• Meiosis


  A form of cell division that gives rise to genetic variation, produces haploid gametes
• Genetic variation in meiosis

  • Crossing over of chromatids
  • Independent assortment of chromosomes
• Meiosis I


  1. Prophase I

  2. Metaphase I

  3. Anaphase I

  4. Telophase I
• Meiosis II


  1. Prophase II

  2. Metaphase II

  3. Anaphase II

  4. Telophase II
• Tissue


  Cells grouped together to perform a common function
• Xylem


  • Transport water and minerals
  • Provide structural support
  • Made of dead tissue with open ends
  • Thickened with lignin
  • Consist of parenchyma, fibres and vessels
• Phloem


  • Tubes made of living cells
  • Involved in translocation of food substances and nutrients
  • Meristem tissue produces cells that elongate and line up end-to-end
  • Have perforated sieve plates
  • Have metabolically active companion cells
• Epithelial tissue


  • Sheet of cells that serves as a lining/cover a surface
  • Squamous type is smooth, flat and very thin
  • Ciliated type has column shaped cells with cilia that move together to move mucus
• Stem cells


  Undifferentiated cells that can develop into any cell type
• Differentiation


  The process by which a cell specialises to carry out a particular function
• Specialised cells


  • Sperm cells
  • Palisade cells
  • Root hair cells
  • Guard cells
• Sperm cells


  • Male gametes, adapted to reach, penetrate and fertilise the ovum
• Palisade cells


  • Most basic plant cell type, contain many chloroplasts and are specialised for photosynthesis
• Root hair cells


  • Specialised epidermal cells with thin and long extensions to increase surface area and contact with water and minerals
• Guard cells


  • Found in pairs in the epidermis of leaves, control the opening and closing of stomata, contain chloroplasts