Cell Division, Diveristy and Organisation

• Mitosis


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


  A series of events a cell goes through, including growth and division, to produce daughter cells
• The role of mitosis and the cell cycle is to produce identical daughter cells for growth and asexual reproduction of cells
• Mitosis does not give rise to genetic variation as all the cells produced are genetically identical
• Cell cycle


  1. Cell forms

  2. Cell grows

  3. Cell divides to form daughter cells
• Cell cycle


  • It is 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, producing haploid gametes
• Meiosis


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


  1. Homologous chromosomes separate

  2. One chromosome of every pair per gamete
• Meiosis II


  1. Another round of cell division occurs

  2. Centromeres split, separating chromatids

  3. Four haploid daughter cells formed
• Tissues


  Groups of cells that work together to perform a common function
• Tissues


  • Xylem
  • Phloem
  • Epithelial
  • Connective
  • Muscle
  • Nervous
• Xylem


  Transport water and minerals, provide structural support, made of dead tissue with open ends, thickened with lignin
• Phloem


  Tubes made of living cells involved in translocation, movement of food substances and nutrients, have perforated sieve plates, have metabolically active companion cells
• Epithelial


  Sheet of cells that line/cover a surface, includes squamous and ciliated types
• Stem cells


  Undifferentiated cells that can develop into various cell types, used in research and medicine
• Differentiation


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


  Red blood cells that transport oxygen, relatively short-lived
• Neutrophils


  White blood cells involved in attacking and destroying foreign microorganisms through phagocytosis
• Meristems


  Dividing plant cells that give rise to xylem and phloem tissue
• 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, long extensions to increase surface area and maximise water and mineral absorption
• Guard cells


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