Key Concepts

• Eukaryotic cells


  Animal and plant cells
• Prokaryotic cells


  Bacterial cells
• Structures in eukaryotic cells

  • Cell membrane
  • Cytoplasm
  • Nucleus containing DNA
• Structures in prokaryotic cells

  • Cell wall
  • Cell membrane
  • Cytoplasm
  • Single circular strand of DNA and plasmids
• Organelles


  Structures in a cell that have different functions
• Organelles in animal and plant cells


  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Mitochondria
  • Ribosomes
• Additional organelles in plant cells


  • Chloroplasts
  • Permanent vacuole
  • Cell wall
• Structures in bacterial cells


  • Cytoplasm
  • Cell membrane
  • Cell wall
  • Chromosomal DNA (circular)
  • Plasmids
  • Flagella
• Differentiation


  A process that involves the cell gaining new sub-cellular structures in order for it to be suited to its role
• Specialised animal cells


  • Sperm cells
  • Egg cells
  • Ciliated epithelial cells
• Specialised plant cells

  • Root hair cells
  • Xylem cells
  • Phloem cells
• Light microscope


  Has two lenses, usually illuminated from underneath, maximum magnification of 2000x, resolving power of 200nm
• Electron microscope


  Uses electrons instead of light, can achieve magnification up to 2,000,000x and resolving power of 10nm (SEM) and 0.2nm (TEM)
• Electron microscopes have allowed the discovery of viruses and detailed examination of proteins
• Magnification


  Magnification of the eyepiece lens x magnification of the objective lens
• Size of an object


  Size of image/magnification = size of object
• Standard form

  Multiplying a number by a power of 10 to get bigger or smaller, with the 'number' between 1 and 10
• Orders of magnitude

  Understanding how much bigger or smaller one object is compared to another
• Prefixes

  • Centi (0.01)
  • Milli (0.001)
  • Micro (0.000,001)
  • Nano (0.000,000,001)
• Using a light microscope

  1. Place slide on stage

  2. Look through eyepiece

  3. Turn focus wheel

  4. Start with lowest magnification
• Preparing a slide


  1. Take thin layer of cells

  2. Add chemical stain

  3. Apply cells to slide

  4. Lower coverslip
• Enzymes


  Biological catalysts that increase the rate of reaction without being used up
• Active site


  The uniquely shaped site on an enzyme where the substrate binds
• Lock and key hypothesis


  The shape of the substrate is complementary to the shape of the active site, forming an enzyme-substrate complex
• Ion


  Measured size / actual size
• Actual size

  Measured size / magnification
• Total magnification


  Objective lens magnification x eyepiece lens magnification
• Enzymes


  Biological catalysts (a substance that increases the rate of reaction without being used up)
• Enzymes


  • They are present in many reactions - allowing them to be controlled
  • They can both break up large molecules and join small ones
  • They are protein molecules and the shape of the enzyme is vital to its function
• Eukaryotic cells


  Animal and plant cells
• Prokaryotic cells


  Bacterial cells
• Active site


  Where the substrate binds
• Structures in eukaryotic cells

  • Cell membrane
  • Cytoplasm
  • Nucleus containing DNA
• Structures in prokaryotic cells

  • Cell wall
  • Cell membrane
  • Cytoplasm
  • Single circular strand of DNA and plasmids
• Organelles


  Structures in a cell that have different functions
• Organelles in animal and plant cells

  • Nucleus
  • Cytoplasm
  • Cell membrane
  • Mitochondria
  • Ribosomes
• Organelles only in plant cells


  • Chloroplasts
  • Permanent vacuole
  • Cell wall
• Lock and Key Hypothesis

  1. The shape of the substrate is complementary to the shape of the active site (matches the shape of the active site), so when they bond it forms an enzyme-substrate complex

  2. Once bound, the reaction the reaction takes place and the products are released from the surface of the enzyme
• Structures in bacterial cells


  • Cytoplasm
  • Cell membrane
  • Cell wall
  • Chromosomal DNA (circular)
  • Plasmids
  • Flagella
• Differentiation


  A process that involves the cell gaining new sub-cellular structures in order for it to be suited to its role