Cells, Cell Transport and Division

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Cells, Cell Transport and Division

• Microscopes

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Use of Microscope

• To magnify objects that cannot be seen with the
  naked eye
• Resolving power
• Ability of microscope to distinguish objects as
  separate measured in nm and the lower the
  number the smaller the object that can be
  distinguished

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Types of Microscopes

• Stereo/dissecting microscope
• 3D images
• Relies on light on top of image
• Low magnification
• Compound light microscope
• Magnifies up to 2000 times
• Resolving power 500 nm

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Compound Light Microscope
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Types of Microscopes

• Electron Microscopes
• Transmission electron microscope (TEM)
• Magnify hundreds of thousands of times
• Resolution as great as 0.2 nm
• Scanning electron microscope
• 3D image
• Lower magnification than TEM
• Sample must be frozen or embedded on plastic
  not living

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Transmission Electron Microscope (TEM) 1
Electronen cannon in the upper part of the
column. 2 Electro-magnetic lenses to direct and
focus the electron beam inside the column. 3
Vacuum pumps system. 4 Opening to insert a grid
with samples into the high-vacuum chamber for
observation. 5 Operation panels (left for
alignment right for magnification and focussing
arrows for positioning the object inside the
chamber). 6 Screen for menu and image display.
7 Water supply to cool the instrument.
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Scanning Electron Microscope (SEM) 1 Electron
cannon in the upper part of the column (here a
so-called field-emission source). 2
Electro-magnetic lenses to direct and focus the
electron beam inside the column. 3 Vacuum pumps
system. 4 Opening to insert the object into the
high-vacuum observation chamber in conventional
SEM mode. 5 Operation panel with focus,
alignment and magnification tools and a joystick
for positioning of the sample. 6 Screen for menu
and image display. 7 Cryo-unit to prepare
(break, coat and sublimate) frozen material
before insertion in the observation chamber in
Cryo-SEM mode. 8 Electronics stored in cupboards
under the desk. 9 Technicians Mieke Wolters-Arts
and Geert-Jan Janssen discussing a view
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Compound Light Microscope
Ocular
Body tube
Revolving nosepiece
Arm
Low power objective
Medium power objective
Stage
High power objective
Coarse Adjustment
Stage clips
Diaphragm
Fine Adjustment
Light source
Base
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Function of parts

• The tube that supports the eyepiece
• The rotating device that holds the objectives
• A small lens with low magnifying power
• A medium lens with medium magnifying power
• A large lens with high magnifying power

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Function of parts

• 6. Metal clips that hold a slide onto the stage
• 7. An adjustable opening under the stage,
  allowing different amounts of light onto the
  stage
• Directs light upwards onto the stage
• A lens where you place your eye
• The attaches the ocular and body tube to the base

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Function of parts

• 11.The platform on which a slide is placed
• 12. A knob that makes large adjustments to the
  focus
• 13. A knob that makes small adjustments to the
  focus (it is often smaller than the coarse focus
  knob)
• 14. This supports the microscope

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Measuring with a Microscope

• Find diameter of field of view
• Estimate the number of objects that will fit
  across the field of view
• Divide this number into the diameter of field
• Ex. Diameter 1000 µm across 2.5
• 1000/2.5 400 µm

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How do you work out the magnification of your
microscope?

• Ocular magnification X Objective magnification

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Microscope Techniques

• Making a wet slide
• Add a drop of water to center of slide
• Place object in water (do not let it get folded)
• Use forceps to position coverslip (fingerprints
  will interfere)
• Lower coverslip slowly to avoid air bubbles

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A wet mount slide
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Microscope Techniques

• Staining or Adding Substances to Slide
• Place drop of stain beside one edge of coverslip
• Touch a small piece of paper towel to opposite
  edge of coverslip
• Towel will absorb H2O and draw stain under
  coverslip

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Staining Technique