Cell Biology & Microscopy Required Practicals

Microscopy Practical

Preparing microscope slide with onion skin
1
Preparing the Slide
  1. Take a clean, glass microscope slide
  2. Peel a thin layer of onion skin using your fingers or forceps or tweezers
  3. Place the thin layer of onion skin onto the slide
  4. Stain the layer of onion skin with iodine solution - this makes the onion skin more visible
  5. Place a cover slip over the iodine-stained layer of onion skin
Safety Concerns
  • Hold slide on the edges to avoid finger marks
  • Avoid iodine solution skin contact
Setting up the microscope with prepared slide
2
Setting up the Microscope
  1. Place the slide onto the microscope stage
  2. Ensure that the lens is, at first, set to the lowest magnification
  3. Using the coarse focus knob, twist until the stage is as close as possible to the lens
  4. Switch on the microscope's light
Safety Concerns
  • Adjust stage height carefully - avoid contact between lens and the slide on the stage
  • Do not stare directly at the light source
Adjusting microscope focus to view specimen clearly
3
Adjusting the Focus
  1. Look through the eyepiece
  2. Using the coarse focus knob, turn until the specimen is in focus
  3. Using the fine focus knob, further focus the specimen
  4. Switch lenses to ones of higher magnification
  5. Use the fine focus knobs to refine focus when using the new lenses
Safety Concerns
  • When switching lenses, be careful to ensure that the lens does not come into contact with the slide on the stage



Osmosis Practical

Using a cork borer on a potato
1
Obtaining Potato Cylinders
  1. Using a cork borer, hollow out 5 cylinders of potato
  2. Using a ruler, cut each cylinder to an equal length of 3cm
  3. Using a paper towel, gently blot dry each cylinder
  4. Weigh each cylinder and record their initial mass
Safety Concerns
  • Be careful when using a sharp knife
Potato cylinders in test tubes
2
Submerging in Solutions
  1. Take 5 boiling tubes
  2. In one boiling tube, pour distilled water
  3. In the other boiling tubes, pour four different concentrations of sugar solution
  4. Put the potato cylinders into the boiling tubes
  5. Leave the potato cylinders in the solutions for some time
  6. After some time, remove the potato cylinders, gently blot them dry with a paper towel, and measure their final length and mass. Compare the final measurements with the initial measurements
Safety Concerns
  • Do not drink ditilled water