Revision

• Prokaryotic


  Cells without a nucleus
• Eukaryotic


  Cells with a nucleus
• Cell cycle (Mitosis)


  1. Interphase

  2. Mitotic phase
• Interphase


  • Cell grows, copies its genetic material (DNA)
• Mitotic phase


  • Cell separates its DNA into two sets and divides its cytoplasm, forming two new cells
• Mitosis


  1. Prophase

  2. Metaphase

  3. Anaphase

  4. Telophase

  5. Cytokinesis
• Resting phase (G0)


  Cell has left the cycle and has stopped dividing
• Meiosis

  1. Cell division in sexually reproducing organisms

  2. Each daughter cell receives half the amount of DNA as the parent cell

  3. Production of gametes (female egg cells, male sperm cells)
• Life first emerged at least 3.8 billion years ago
• Cells originated in a sea of organic molecules, get food and energy directly from their environment
• Prokaryotes


  • Bacteria
• Eukaryotes


  • Much more complex - contain nucleus, variety of cytoplasmic organelles
• Cell features (Prokaryotes)


  • Small cells (<5 μm)
  • Always unicellular
  • No nucleus or any membrane-bound organelles, such as mitochondria
  • DNA is circular, without proteins
  • Ribosomes are small (70S)
  • No cytoskeleton
  • Motility by rigid rotating flagellum (made of flagellin)
  • Cell division is by binary fission
  • Reproduction is always asexual
  • Huge variety of metabolic pathways
• Cell features (Eukaryotes)


  • Larger cells (>10 μm)
  • Often multicellular
  • Always have nucleus and other membrane-bound organelles
  • DNA is linear and associated with proteins to form chromatin
  • Ribosomes are large (80S)
  • Always has a cytoskeleton
  • Motility by flexible waving cilia or flagellae (made of tubulin)
  • Cell division is by mitosis or meiosis
  • Reproduction is asexual or sexual
  • Common metabolic pathways
• Eukaryotic cells


  Cells with a nucleus