cell biology (1)

• Eukaryotes


  Animals and plants. They are larger and more complex.
• Plant cell


  • Nucleus-Contains Genetic material and controls the activity of the cell
  • Cytoplasm-A gel like substance where many chemical reaction takes place
  • Cell membrane-Controls what enters and leaves the cells
  • Cell wall-Made of cellulose and strengthens the cell
  • Sap vacuole-Contains a weak solution of salt and sugar
  • Chloroplast-Where photosynthesis takes place
  • Ribosome-Where proteins synthesise
  • Mitochondria-Where aerobic respiration takes place in the form of ATP, it supplies energy to the cells
• Prokaryotes


  Bacterial cells with no nucleus or subcellular structures with membranes
• Nerve cell


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


  • Mid piece with mitochondria
  • Tail
  • Acrosome
• 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
• Simple microscope


  Low magnification, low resolving power
• Electron microscope


  High magnification, high resolving power
• Millimeter


  One thousandth of a meter
• Micrometer


  One thousandth of a millimeter
• Nanometer


  One thousandth of a micrometer
• Magnification calculation


  Size of image / Size of real object
• Culturing microorganisms


  1. Binary fission

  2. Provide nutrients (glucose, amino acids, mineral ions)

  3. Incubate at 25°C
• Growing uncontaminated cultures


  1. Sterilise equipment

  2. Inoculate agar plate

  3. Seal plate

  4. Incubate upside down
• Testing antibiotics/antiseptics


  1. Place discs on agar with bacteria

  2. Measure area of dead bacteria
• Control variables


  • Disc area
  • Concentration of antibiotic/antiseptic
  • Volume of antibiotic/antiseptic
• Cell cycle


  1. Growth and DNA replication

  2. Mitosis (chromosomes line up, divide, cytoplasm divides)

  3. Genetically identical daughter cells
• Stem cells


  Undifferentiated cells that can develop into specialised cells
• Embryonic stem cells come from the early embryo
• 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
• 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 loses mass

  Solution outside is more concentrated than inside, so water moves out by osmosis
• Potato tissue gains mass

  Solution inside is more concentrated than outside, so water moves in by osmosis
• Animal cell

  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Mitochondria
  • Ribosomes