3. Preparing Microscope Slides Flashcards
Temporary mount.
Method of preparing a microscope slide in which the specimen is suspended in a drop of liquid.
Dry mounts.
Specimen is put on slide without being suspended in liquid.
What type microscope would you use if you were using temporary mount?
Optical microscope.
STEP 1
Pipette small drop of water onto centre of the slide.
STEP 2
Use tweezers to place a thin section of specimen on top of water drop.
Your specimen needs to let light pass through it for you to be able to see it clearly under microscope so if you’ve got thick specimen you’ll need to take a think slice to use on slide.
STEP 3
Add drop of stain to highlight objects in cell
EXAMPLES - eosin used to make cytoplasm show up.
Iodine in potassium iodide solution used to stain starch grains in plant cells.
STEP 4
Add cover slip (clear glass/plastic that protects specimen)
Stand slip upright on slide next to water droplet and carefully tilt and lower cover so the specimen.
Try not to get air bubbles - obstruct view of specimen.
Disadvantages of using temporary mounts
Can’t be stored for long
What are temporary mounts the best for looking at?
Organisms that live in water
Artefacts
Things you can see down the microscope that aren’t part of cell or specimen.
Dust / bubbles / fingerprints.
Usually made during preparation of specimen.
Where will you mostly find artefacts?
Electron microscopes because specimen needs a lot of preparation.
First scientists that used electron microscopes couldn’t properly distinguish between artefacts and organelles, what did they have to do?
Repeatedly prepare specimens in different ways.
If an object could be seen with one preparation technique but not another, it was more likely to be an artefact than an organelle.
