Introduction
Greg Foot explains the main differences between light and electron microscopes
Even larger human cells - like the skin cell - are 20 times smaller than a grain of salt. A red blood cell is much smaller than that.
To allow us to see detail in these cells, we need the help of a microscope.
Making slides
A slide is a thin piece of glass used to hold objects which are examined under a microscope.
Most slides will already be made up for you. If you do get the chance to prepare your own slide, here’s what to do:
Plant cells
- Peel a thin, transparent layer of epidermalProtective outer layer of skin however, in this instance, it is a single layer of cells found inside an onion. cells from the inside of an onion.
- Place cells on a microscope slide.
- Add a drop of water or iodine (a chemical stain).
- Lower a coverslip onto the onion cells using forceps or a mounted needle. This needs to be done gently to prevent trapping air bubbles.
Animal cells
- Remove cells from the inside of your cheek using a cotton bud.
- Smear the cotton bud onto a microscope slide.
- Add a drop of methylene blue (a chemical stain).
- Lower a coverslipSmall, square of glass placed on top of a specimen to prevent the cells drying out and to protect the microscope lens should it have contact with the slide. onto the cheek cells using forceps or a mounted needle. This needs to be done gently to prevent trapping air bubbles.
Chemical stains are used to make some cell parts more obvious.
