Structure of plant and animal cells under an electron microscope Advanced Higher Biology Cell and molecular Biology

The Electron Microscope Two main advantages High resolving power (short wavelength of electrons) As electrons negatively are charged the beam can be focused using electromagnets As electrons are absorbed by molecules of air, a near-vacuum has to be created within the chamber of an electron microscope.

The Electron Microscope Two types Transmission Electron Microscope (TEM) Scanning Electron Microscope (SEM) Activity Read through the handout on the electron microscope Answer discussion questions 1 - 4

Comparison of advantages and disadvantages of the light and electron microscopes Light Microscope Advantages Electron Microscope Disadvantages Small and portable very large Operated in special rooms Unaffected by magnetic fields Affected by magnetic fields Preparation of material is quick and simple Preparation of material is lengthy Requires expertise Material rarely distorted by preparation Preparation may distort material Natural colour of object observed Images are in black and white Cheap to purchase and operate Expensive to purchase and operate

Comparison of advantages and disadvantages of the light and electron microscopes Light Microscope Disadvantages Electron Microscope Advantages Magnifies objects up to 1500x only Magnifies objects more than 500 000X Depth of field is restricted Possible to investigate a greater field of depth

Comparison of pathways of the light and electron microscopes

Ultrastructure of an animal cell as seen through an electron microscope

Ultrastructure of a plant cell as seen through an electron microscope

Pupil Activity Cell structure Read through the information on each of the organelles as you colour them in Follow the guidance on colouring them in given at the bottom of the page This works on the theory that whilst you are colouring in, you have time to consider and think about the structure and function of the organelles