Topic: Microscope

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• Topic Microscope
• MI Explain the function of microscopes.
• Do Now What do we use to observe cells more
  closely?
• HW study for Wednesdays test

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• Microscope

• Instrument that produces a larger image of an
  object (specimen) using lenses

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• Lens

• Piece of curved glass
• Causes light rays to come together or spread
  apart as they pass through
• Magnify an image

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• Simple
• Microscope

• Uses 1 lens and light to magnify the specimen

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• Compound
• Light
• Microscope

• Uses 2 lenses light to magnify specimen
• Need stain (dye) to see it

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Blood
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Cheek Cells 40x
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Onion Cells 10x
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• Phase
• Contrast
• Microscope

• View living specimens without staining

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Cheeks cells as they would appear without iodine
with a compound microscope.
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Same image with phase contrast objectives. White
dots inside each cell are the nuclei.
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Light microscope
Phase contrast microscope
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• Human lymphocyte (phase-contrast microphotograph).

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Phase contrast light micrograph of Paramecium
highlighting the two contractile vacuoles
including the radial arms each composed of
ampulla and collecting canal.
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• Electron microscope illuminates the specimen and
  can magnify image up to 100,000x
• Uses beam of ELECTRONS instead of light

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Fly
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Spider
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Termite head
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Tapeworm
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Blood
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Pollen Grains
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• Scanning electron microscope image of a leaf from
  a Black Walnut tree. Image shows a cross-section
  of a cut leaf, its upper epidermal layer,
  mesophyll layer with palisade cells and vascular
  bundles, and lower epidermal layer. The
  protrusion at center is just over 50 microns
  tall. (Dartmouth Electron Microscope
  Facility/Dartmouth College)

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Hair
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PARTS OF A MICROSCOPE
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• eyepiece

• Ocular lens (usually 10x)
• Lens you look through

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• Objective
• lenses

• Contains lenses
• Low, medium, high power

Low Power
High Power
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A
B
Low Power Larger Field of view
High Power Smaller Field of View
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• Low power objective used to locate the specimen
  on the slide
• Larger field of view (See more of the slide)
• High power objective
• More magnification
• Smaller field of view

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• Nosepiece

• Holds rotates obj. lenses

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• Body Tube

• Connects eyepiece to nosepiece

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• Supports body tube

• Arm

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• Bottom support

• Base

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• Where slide is placed

• Stage

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• Hold slide in place

• Stage
• Clips

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• Illuminates specimen, provides light

• Mirror/ light

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• Diaphragm

• Controls the AMOUNT of light used

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• 10/23/08
• Aim How do we use a microscope?
• Do Now DONT COPY THE QUESTIONS!!!!
• Which objective gives you a larger field of view?
• Which structure is used to adjust the amount of
  light reaching the specimen?
• If your searching for a cell on your slide, which
  objective should you use?
• HW Ditto Parts of a Compound Microscope

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• Larger focusing knob

• Coarse
• Adjustment
• Knob

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• For focusing under LOW POWER ONLY
• If used under high power, the objective lens
  and/or slide can break

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• Sharpens image
• Focusing for High Power

• Fine
• Adjustment
• Knob

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• Review Identify the structure being described.
• Used to focus the specimen under high power.
• Adjusts the amount of light reaching the
  specimen.
• Objective used to view a larger field of view
  needed to search for a specimen.
• Used to focus specimen under low power.
• Contains lenses.

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MI How do we use a microscope?
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• Eyepiece lens magnification
  x
  objective lens magnification

• Total
• magnification

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Total magnification4 x10 40
50
100x
400x
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• Rules
• when
• using a
• microscope

• 1. Carrying microscope
• one hand on arm, other hand under base close to
  your body

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• 10/24/08
• Aim Using the Microscope
• Do Now Give the total magnification for the
  following
• Ocular is 10x and objective used is 35x
• Ocular is 10x and the objective used is 5x
• HW Bring in your signed progress report and
  continue researching and working on your science
  fair project.

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• 2. DO NOT use the coarse adjustment under high
  power
• bc it can break the lens or the slide

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• 3. Always start off with low power bc it gives
  you a greater field of view.

LOW
HIGH
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• 4. Before switching to high power you must
• - focus your image
• - center your image

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• 5. When switching from low to high power, amount
  of light decreases. Make sure you adjust the
  diaphragm.

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• 6. When cleaning a lens, use LENS PAPER.
• Do not use a napkin, or paper towel

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• Staining

• Make cell parts more visible

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Unstained cheek cells
Stained cheek cells
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• Examples
• 1. Lugols Iodine (plant cells)

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Onion Cells stained with Lugols Iodine
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• 2. Methylene blue (animal cells)

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Cheek Cells
Unstained
Stained
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Skin Cells stained with Methylene Blue
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• Wet
• mount

• 1. Place a drop of water on the slide

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• 2. Place object on the slide.

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• 3. Slowly lower the cover slip onto specimen on
  an angle to avoid AIR BUBBLES.

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• 4. Excess water should be absorbed with a paper
  towel.

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• Upside down backwards

• How do
• images
• appear?

On the slide
Seen through lens
F
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• 10/27/08
• Aim Using the Compound Microscope
• Do Now
• Which objective gives a smaller field of view
  low or high power?
• Which field of view is usually darker high or
  low power? What structure would you use to adjust
  the amount of light?
• HW Finish labeling the microscope picture on the
  lab.

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• Image moves in opposite direction

• What
• happens
• when
• you
• move
• the
• slide?

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• Review
• Explain one rule that must be followed when using
  the microscope.
• What do we use to make cell parts more visible?
• Which way will a cell appear to move when moving
  the microscope to the left and down?
• What happens to the image of the specimen when
  viewed with a microscope?