Microscopes – Revise

Microscopes

There are 2 important types of microscopes you should know about. They are: 

  • Light Microscope
  • Electron Microscope

You can use a light microscope in a practical looking at onion cells or your own cheek cells. But what are the differences between the these two different microscopes?

A light microscope is used to see individual cells and larger organelles* e.g. the nucleus or mitochondria

An electron microscope is used to see the finer detail and smaller organelles e.g. ribosomes or the detail/structure inside of the mitochondria

*organelles – the parts of the cell, we have organs and the cells have organelles

*resolution – the ability to distinguish 2 points of detail before they become unclear. A higher resolution means a clearer (sharper) image.

You can see some of the structures of an animal cell or plant cell under a microscope with two simple practicals. Below are example methods and what you should be able to see under the micropsope. 

Looking at animal cells under a micropsope

Method

Gently chew the side of your cheek for 2 minuets, be sure not to draw any blood

  1. Using a sterile swab, swab the inside of your cheek
  2. Rub your swab onto the centre of a microscope slide to transfer the cheek cells
  3. Add 1 or 2 drops of Methylene Blue
  4. Place a cover slip over the now stained cheek cells
  5. Using a microscope appropriately look at the cheek cells and try and draw/label what you can see *
You should be able to identify 3 things in your cheek cells. These are the nucleus, cell membrane and cytoplasm.
 
 
Cheek cells under a microscope

Looking at plant cells under a micropsope

Method

You or your teacher should cut a small square section of an onion

  1. Using a pair of tweezers pull away the inner layer of the onion. This should be very thin as it should be a single layer of cells
  2. Transfer the cell sample onto you Microscope slide ensuring it is flat
  3. Add 1 or 2 drops of Iodine Solution
  4. Place a cover slip over the now stained onion cells
  5. Using a microscope appropriately look at the onion cells and try to draw/label what you can see *
 You should also be able to identify the nucleus, cytoplasm and cell wall of the plant cells. 
Onion cells under a microscope

* You may be asked to work out the magnification or actual size of the cheek cell.