Cell Biology

• Eukaryotes

  Animals and plants
• Animal cell


  • Nucleus
  • Cytoplasm
  • Cell membrane
• Plant cell


  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Cell wall
  • Sap vacuole
  • Chloroplast
• Prokaryotes


  Bacterial cells with no nucleus or subcellular structures with membranes
• Approximate sizes: Animal cell 10 micrometers, Plant cell 50 micrometers, Prokaryote 5 micrometers
• Nerve cell

  • Cell body
  • Dendrites
  • Axon
  • Insulating sheath
  • Axon terminals
• Sperm cell


  • Mid piece with mitochondria
  • Tail
  • Acrosome
  • Nucleus
• Muscle cell


  • Fibers for contraction
  • Mitochondria
  • Glycogen store
• Xylem cell

  • No end plates
  • No cytoplasm
  • Lignin rings for support
• Phloem cell


  • Little cytoplasm
  • End plates with pores
  • Companion cells
• Root hair cell

  • Large surface area
  • Many mitochondria
• Microscopes

  Simple microscopes have low magnification and resolving power

  Electron microscopes have high magnification and resolving power
• Calculating magnification

  Magnification = Size of image / Size of real object
• Culturing microorganisms


  Binary fission for rapid division

  Provide nutrients like glucose and amino acids

  Incubate at 25°C to encourage growth
• Growing uncontaminated cultures

  Sterilise equipment and work area

  Use inoculating loop to transfer bacteria to agar plate

  Seal plate to prevent contamination

  Incubate at 25°C
• Testing antibiotics/antiseptics


  Place antibiotic/antiseptic discs on agar with bacteria

  Measure area of dead bacteria around discs

  Control variables: disc area, concentration, volume
• Cell cycle and mitosis


  Stage 1: Cell growth and DNA replication

  Stage 2: Chromosomes line up and separate

  Stage 3: Cytoplasm and cell membrane divide
• Stem cells


  Undifferentiated cells that can develop into specialised cells
• Cell growth and division


  1. Cell grows and increases number of subcellular structures

  2. DNA replicates to form two copies of each chromosome

  3. Chromosomes line up along center and are pulled to each end of cell

  4. Cytoplasm and cell membranes divide to form two genetically identical cells
• Mitosis


  The process of cell division described above
• Types of stem cells

  • Embryonic stem cells
  • Adult stem cells
  • Plant stem cells (meristem tissue)
• Embryonic stem cells

  • Undifferentiated
  • Can be cloned
  • Can differentiate into most other cell types
• Adult stem cells

  • Found in bone marrow
  • Can differentiate into many cell types, mainly blood cells
• Plant stem cells

  • Found in meristem tissue in root and shoot tips
  • Can differentiate into any plant cell
• Therapeutic cloning


  1. Patient body cell nucleus removed and inserted into empty human egg cell

  2. Cloned to produce stem cells

  3. Stem cells differentiated to make specialized cells/tissues for treatment
• Diffusion


  Spreading out of particles in a solution or gas, with net movement from higher to lower concentration
• Factors affecting rate of diffusion

  • Concentration gradient
  • Temperature
  • Surface area
• Active transport


  Movement of particles from lower to higher concentration, requires energy
• Active transport examples


  • Sugar absorption in small intestine
  • Mineral ion absorption in plant root hair cells
• Surface area to volume ratio

  Ratio of surface area to volume, decreases as organism size increases
• Adaptations for exchange systems in larger organisms


  • Villi and microvilli in small intestine
  • Alveoli in lungs
  • Stomata in leaves
  • Gill filaments in fish
• Osmosis


  Diffusion of water from dilute to concentrated solution through partially permeable membrane
• Investigating effect of solutions on plant tissue mass

  1. Prepare solutions of different concentrations

  2. Cut equal-sized plant tissue samples

  3. Immerse samples in solutions

  4. Measure mass change after time
• Potato tissue mass change

  • Decreases in more concentrated solution (water moves out)
  • Increases in more dilute solution (water moves in)
• Point where no net mass change occurs is where internal and external concentrations are equal