biology

• Eukaryotes


  Often multicellular (in groups/ cells need to share tasks), 100-1000 times larger than a prokaryote
• Prokaryotes


  Unicellular (can function on its own), less complex
• Eukaryotic cells


  • Animal cells
  • Plant cells
  • Algae cells
• Bacterial cells


  Prokaryotic cells
• Animal cell organelles


  • Nucleus
  • Cell membrane
  • Mitochondria
  • Cytoplasm
  • Ribosome
• Plant cell organelles


  • Chloroplast
  • Cell wall
  • Vacuole
• Sperm cell


  • Carries male DNA to egg cell (ovum) for successful reproduction
  • Enzymes in acrosome break down cell membrane of egg cell
  • Long tail to assist swimming
  • Mitochondria to provide energy for movement
• Nerve cell


  • Carries nerve impulses throughout the body
• Egg cell


  • Fertilised by sperm cell
• Muscle cell


  • Helps the body to move
• Red blood cell


  • Transports oxygen around the body
• White blood cell


  • Fights pathogens that cause disease
• Ciliated epithelial cell


  • Sweeps dust and microorganisms away from the lungs
• Palisade cell


  • Carries out photosynthesis to make glucose
• Cell differentiation


  When a cell changes to become specialised at its job
• Cell differentiation process (animal cells)

  1. Starts off as a ball of unspecialised cells

  2. More cell division -> divided stem cells take up different tasks
• Plant cells never lose the ability to differentiate
• Resolving power/resolution


  The ability to distinguish between two separate points that are very close to each other
• Magnification


  Ability to make small objects seems larger
• Image size


  Actual size x magnification
• Light microscopes


  • Lower magnification/resolution, cheaper
• Electron microscopes


  • Higher magnifications/resolution (can observe mitochondria/ribosome), expensive
• Bacterial reproduction: Binary fission


  1. Circular DNA + plasmids replicate

  2. Cell gets bigger + circular DNA strands move to opposite ends

  3. Cytoplasm begins to divide + new cell walls form

  4. Cytoplasm divides -> 2 new identical daughter cells formed
• Optimal conditions for bacteria reproduction


  Warm temperatures + lots of nutrients
• Binary fission completes a cycle every 20 minutes