Bio lab

• Microscope


  A laboratory instrument used to examine objects that are too small to be seen by the naked eye

  
• Resolving power


  The minimum distance two points can be separated and still be distinguished as two points
• Magnification


  The ratio of an object's image size to its real size
• Contrast


  Increasing differences between the lightest and darkest parts of an image, making them easier to distinguish
• Parts of a microscope

  • Mechanical system
  • Illuminating system
  • Imaging system

  
• Mechanical system


  • Forms the skeleton of microscope and includes the tube, arms, nosepiece, base, stage, and focusing knobs
• Illuminating system


  • Concentrates light on specimen and usually consists of a light source, a condenser lens and an iris diaphragm
• Imaging system


  • Magnifies the image of the specimen and improves its resolution and includes ocular and objective lenses
• Microscope parts


  • Arm
  • Focusing knobs
  • Base
  • Stage
  • Nosepiece
  • Tube
  • Body tube
  • Nosepiece
  • Stage
  • Stage clips
  • Coarse adjustment knob
  • Fine adjustment knob
  • Condenser lens
  • Light source
  • Iris diaphragm
  • Ocular lens or eyepiece
• Microscope operation


  1. Carry the microscope

  2. Place microscope on bench

  3. Clean lenses and slides

  4. Plug in and turn on light

  5. Rotate nosepiece to proper objective

  6. Place slide on stage

  7. Start on low power, shift to higher powers

  8. Focus image using fine adjustment

  
• Proper microscope storage at end of use
• Light microscope

  Magnification 4-50X, specimen moved same direction as image, reflected light

  
• Electron microscope


  Magnification may reach 1,000,000X, resolution 0.2 nm, sections 60-100 nm thick, stained with heavy metals, used to study cell ultrastructure

  
• Scanning electron microscope


  Scans surface of specimen coated with thin gold layer, uses electron beams for illumination
• Robert Hooke was the first scientist to view cells under a microscope
• Common features of all cells


  • Plasma membrane
  • Nucleus
  • Cytoplasm
  • Ribosomes
• Prokaryotic cells


  Do not have an organized nucleus, relatively small (1-10 μm), include bacteria
• Eukaryotic cells


  Have an organized nucleus enclosed by a nuclear envelope, larger, include animals, plants, protists and fungi
• Basic bacterial cell shapes

  • Cocci
  • Bacilli
  • Spirilli
• Bacteria used to make yogurt

  • Lactobacillus bulgaricus (rods)
  • Streptococcus thermophilus (cocci)
• Photosynthetic prokaryotes


  • Anabaena (filamentous organism)
• Cells from human cheek lining

  • Simple squamous epithelial cells
• Plant cells


  • Onion epidermal cells
  • Tomato pulp cells with chromoplasts
• Carbohydrates, lipids, proteins and nucleic acids are biological macromolecules
• Polymers


  Formed by joining one or more building blocks called monomers
• Dehydration synthesis


  Polymers are formed by removal of water
• Hydrolysis


  Separates monomers by adding water
• Carbohydrate classification


  • Monosaccharides
  • Disaccharides
  • Polysaccharides
• Monosaccharides


  • Glucose
  • Fructose
  • Galactose
• Disaccharides


  • Sucrose
  • Lactose
  • Maltose
• Polysaccharides


  • Starch
  • Glycogen
  • Cellulose
• Reducing sugars


  Sugars that contain a ketone or aldehyde group
• Benedict's test


  Used to detect reducing sugars
• Lugol's test


  Used to detect starch (polysaccharides)
• Amino acids


  The monomers that make up proteins
• Ninhydrin test


  Used to detect proteins
• Procedure for testing for carbohydrates

  1. Fill test tubes to 1 cm with glucose, maltose, sucrose, starch & water

  2. Fill test tubes to 3 cm with Benedict's reagent

  3. Place test tubes in hot water bath (boil for 5 min)

  4. Observe color change
• Benedict's reagent


  Used to test for the presence of reducing sugars
• Carbohydrates tested


  • glucose
  • maltose
  • sucrose
  • starch
• Procedure for iodine test for starch

  1. Fill test tubes to 1 cm with glucose, sucrose, starch, glycogen & water

  2. Add 2 drops of iodine

  3. Observe color change