Key concepts

• Animal cell


  • Nucleus - stores genetic information
  • Cell membrane - controls what enters and exits
  • Mitochondria - responsible for respiration
  • Ribosomes - make essential proteins
  • Cytoplasm - where chemical reactions happen
• Plant cell


  • Cell wall - gives extra strength and protection
  • Vacuole - stores cell sap
  • Chloroplasts - for photosynthesis
• Bacteria cell


  • Flagellum - acts like a 'tail' for movement
  • DNA floats loose in cytoplasm
  • Plasmid loops - extra DNA
• Prokaryotic cells


  Smaller, simpler, no nucleus
• Eukaryotic cells


  Bigger, more complex, have a nucleus
• Differentiation


  Cells switch particular genes on/off to become specialized
• Sperm and egg cells

  • Haploid nucleus - half the normal number of chromosomes
  • Egg has lots of nutrients in cytoplasm
• Ciliated epithelial cell


  • Has hair-like cilia to help move substances along
• Light microscope


  Invented in 1500s, uses light beams, relatively low resolution, can view living cells
• Electron microscope


  Invented in 1930s, uses electron beams, higher resolution, cannot view living cells
• Total magnification


  Eyepiece lens magnification x Objective lens magnification
• Enzymes


  Biological catalysts made by living things, speed up reactions
• Substrate


  The thing the enzyme is reacting with
• Active site


  The place on the enzyme where the substrate fits
• Enzyme specificity


  Enzymes can only catalyze one reaction, one type of substrate can fit
• Enzyme breakdown


  Larger molecules broken down into smaller molecules
• Enzyme synthesis


  Smaller molecules joined together to form larger molecules
• Enzyme temperature


  Optimum temperature for activity, then quickly denatures
• Enzyme pH


  Optimum pH for activity, then begins to denature
• Substrate concentration


  Increases enzyme activity until all active sites are full
• Benedict's test


  Add Benedict's reagent, heat gently, color change indicates reducing sugar concentration
• Biuret test


  Add potassium hydroxide, add copper sulfate, purple color indicates proteins
• Emulsion test


  Add ethanol, shake, pour into water, milky color indicates lipids
• Iodine test


  Add iodine, blue-black color indicates starch
• Calorimetry


  Burn food, measure temperature change of water, calculate energy content
• Diffusion


  Movement of particles from high to low concentration, passive process
• Active transport


  Movement of particles from low to high concentration, requires energy
• Osmosis


  Movement of water molecules from high to low concentration through a partially permeable membrane