Using a Microscope to View Cells

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Using a Microscope to View Cells
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Learning Targets

• I can follow a lab procedure
• I can use prior knowledge, pictures and research
  to make connection and predictions
• between the investigation of the lab and my own
  experiences.
• I can use a microscope to view a microscopic
  image
• I can draw or take a picture a microscopic image
  using a camera and label the parts of the cell
  at 40X and 100X magnification using a compound
  light microscope.
• I can distinguish difference between animal and
  plant cell based on shape, and characteristic
  organelle differences.

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Microscope Procedure and Technique

• Today we will make slides of 3 different cells
  and look at them under the microscope
• 1. Onion skin cells
• 2. Elodea leaf cells
• 3. Human cheek cells
• Microscope rules
• 1. Always carry or move a microscope with two
  hands, one on the arm, and one on the bottom.
• 2. Always use the lowest power lens (the shortest
  lens) when you take a slide on and off the stage.
• 3. Always start with the lowest power lens (the
  shortest lens). Get the slide in focus there,
  first using the coarse focus knob (the large
  knob) to get it close, THEN using the fine focus
  knob (the small knob) to get it perfectly in
  focus. From there, you can switch to a higher
  power lens.
• 4. Always look from the SIDE of the microscope,
  not through the eyepiece, when switching lenses
  to avoid hitting the lens on the slide.
• 5. Only use the coarse focus knob (the large
  knob) when you are using the lowest power lens
  (the shortest lens). Using the coarse focus knob
  on a higher power can crack the lens!
• 6. Please turn off the light and cover the
  microscope when you are finished.

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Preparing the Onion Cell Slide

• Onion skin cells
• 1. Add 2 drops of iodine to the center of a glass
  slide. Be careful! Iodine can stain your clothes.
• 2. Take a small piece of onion. Use tweezers to
  peel off the skin from the underside (the rough,
  white side) of the onion. Throw the rest of the
  onion piece away.
• 3. Carefully lay the onion skin flat in the
  center of the slide on top of the iodine.
• 4. Add 2 drops of iodine to the top of the onion
  skin.
• 5. Stand a thin glass cover slip on its edge near
  the onion skin, next to the drop of iodine.
• 6. Slowly lower the other side of the cover slip
  until it covers the onion skin completely. If
  there are air bubbles, gently tap on the glass to
  chase them out.

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Viewing the Onion Cells Under Low Power (40X)

• 1. Make sure the lowest power lens (the shortest
  lens) is in place over the stage and the
  microscope light is turned on. Place the slide
  onto the stage of the microscope.
• 2. Look through the eyepiece and turn the coarse
  focus knob (the largest knob) until an image
  comes into focus. It should look like a brick
  wall or like lizard skin.
• 3. Now use the fine focus knob (the smallest
  knob) to make the image as focused as possible.
• 4. Take a picture or draw what you see and
  insert it below.

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Viewing Onion Cells Under Medium Power (100X)

• 1. Again, looking from the SIDE of the
  microscope, rotate the lenses to the medium
  powered lens (100x). If you need to, use the fine
  focus knob (the smallest knob) to get the image
  into focus. You may see a dark blob in the middle
  of each cell.
• 2. Try and capture the image with a camera
• 3. Display and labeled the image below.
• 2.In your lab notebook, draw a picture of what
  you see. Label the picture Onion skin cells
  400x. Label as many parts of the cell as you can
  see.
• 3. Switch to the lowest power lens and THEN
  remove the slide. Set it aside for now.

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Viewing the Onion Cells under High Power (400X)

• Increase the power to 400X by turning to the
  largest objective lens.
• Using only fine focus, do your best to focus the
  image
• Draw or take a picture.
• Insert and label the image below
• Switch to the lowest power lens and THEN remove
  the slide. Set it aside for now.

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Preparing the Elodea Leaf Slide

• Preparing the Elodea leaf Slide
• 1. Tear off one small leaf from the elodea plants
  floating in the fish tank.
• 2. Add one drop of tap water to the slide.
• 3. Stand a thin glass cover slip on its edge near
  the leaf, next to the drop of water.
• 4. Slowly lower the other side of the cover slip
  until it covers the leaf completely. Make sure
  there are no air bubbles.
• 5. Make sure the lowest power lens (the shortest
  lens) is in place over the stage. Place the slide
  onto the stage of the microscope.

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Viewing Elodea Cells Under Lower Power (40X)

• 1. Make sure the lowest power lens (the shortest
  lens) is in place over the stage. Place the slide
  onto the stage of the microscope.
• 2. Make sure the lowest power lens (the shortest
  lens) is in place over the stage. Place the slide
  onto the stage of the microscope.
• 3. Look through the eyepiece and turn the coarse
  focus knob (the largest knob) until an image
  comes into focus. It should look like small green
  bricks or like lizard skin.
• 4. Now use the fine focus knob (the smallest
  knob) to make the image as focused as possible.
• 5. In your lab notebook, draw a picture of what
  you see or Take a photo of your drawing. Go on
  line and find an actual picture of elodea cells.
  Label the picture Elodea leaf cells 40x. Label
  as many parts of the cell as you can see.
• Insert image Below

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Viewing Elodea Cells Under Medium Power

• 1.Looking from the SIDE of the microscope, rotate
  the lenses to the 100x lens. If you need to, use
  the fine focus knob (the smallest knob) to get
  the image into focus. You should be able to see
  lots of small green dots in each cell.
• 2.Record an image of the cells by drawing or
  camera and insert it below.

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Elodea at High Power (400X)

• 1. Again, looking from the SIDE of the
  microscope, rotate the lenses to the 400x lens.
  If you need to, use the fine focus knob (the
  smallest knob) to get the image into focus. The
  little green dots should get larger.
• 2. In your lab notebook, draw a picture of what
  you see or take a picture. Insert Your image
  below. Go on line and find an actual picture of
  elodea cells. Label the picture Elodea leaf
  cells 400x. Label as many parts of the cell as
  you can see.
• 3. Switch to the lowest power lens and THEN
  remove the slide. Set it aside for now.

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Preparing the Human Cheek Cell Slide

• Preparing The Slide for Human cheek cells
• 1.Add one drop of methylene blue to the middle of
  a clean slide. Be careful! Methylene blue will
  stain your clothes and skin.
• 2.Use the flat side of a toothpick to gently
  scratch the inside of your cheek. DO NOT GOUGE
  YOUR CHEEK - you dont need chunks of skin and
  definitely dont want to draw blood.
• 3.Gently touch the toothpick to the drop of dye
  on the slide. Some of your cheek cells should
  drift off into the dye.
• 4.Throw the toothpick away.
• 5.Stand a thin glass cover slip on its edge near
  the drop of dye.
• 6.Slowly lower the other side of the cover slip
  until it covers the dye completely. Make sure
  there are no air bubbles.

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Viewing Cheek Cells Under Low Power (40X)

• 1.Make sure the lowest power lens (the shortest
  lens) is in place over the stage. Place the slide
  onto the stage of the microscope.
• 2.Look through the eyepiece and turn the coarse
  focus knob (the largest knob) until an image
  comes into focus. It should look like scattered
  blobs. Move the slide around until a nice cluster
  of blobs moves into the center of your image.
• 3.Use the fine focus knob (the smallest knob) to
  make the image as focused as possible.
• 4. In your lab notebook, draw a picture or take a
  picture of what you see. Take a photo of your
  drawing. Label the picture Human cheek cells
  40x.

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Viewing Cheek Cells Under Medium Power (100X)

• 1. Looking from the SIDE of the microscope, NOT
  through the eyepiece, rotate the lenses to the
  100x lens. If you need to, use the fine focus
  knob (the smallest knob) to get the image into
  focus.
• 2. Draw or take a picture of the image and insert
  below.

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Viewing Cheek Cells Under High Power (400X)

• 1. Looking from the SIDE of the microscope,
  rotate the lenses to the 400x lens. If you need
  to, use the fine focus knob (the smallest knob)
  to get the image into focus.
• 2. In your lab notebook, draw a picture of what
  you see or take photo Take a photo of your
  drawing. Insert the picture below. Go on line
  and find an actual picture of cheek cells. Label
  the picture Human cheek cells 400x. Label as
  many parts of the cell as you can see.
• 3. Switch to the lowest power lens and THEN
  remove the slide.

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Questions and Tasks

• Describe the shape of an animal cell vs. That of
  a plant cells
• What organelles were visible that plant cells
  have but animal cells do not.
• Why did the elodea cells we looked at have
  chloroplast but the onion cells did not?
• Label the images with their cell type and
  magnification based on your images.