1. Microscopy

2. Cell Theory
Living organisms either multicellular (made up of many cells) or unicellular (exist as single cells)
Metabolic processes take place within cells
New cells are derived from existing cells
The genetic material of the organism is passed from parent cells to daughter cells
A cell is the smallest unit of an organism capable of surviving independently
Zooming into DNA

3. Parts of the microscope quiz
Check that lowest power of objective lens is clicked into place
Clip slide onto stage
Ensure that stage is closest to the lens
Look at the stage from the side and position slide so that the specimen is beneath the lens
Look down the eyepiece and carefully turn coarse focus until specimen comes into view
Adjust illumination
Use fine focus to adjust if necessary
To view with higher power make sure that the area of interest is in the centre of the field of view and then rotate objective lenses
Microscopes through
history
Parts of the
microscope quiz

4. Transmission electron microscope
Limit of resolution for light microscope is limited by wavelength of light (red light = 400nm, therefore resolution limit is 200nm) . Tried to use x-rays (smaller wavelength e.m.r.) but can’t focus them easily. Free electrons behave like e.m.r. with a wavelength at least as short as x-rays. The negative charge means that they can be focused using electromagnets: limit of resolution is 0.5nm (cell membrane dimension is 7nm)

5. Electron beam Specimen Copper grid Screen
Human tissue culture cell – false colour
Prostate cancer cell
Electron beam
Specimen
Copper grid
Screen

6. Scanning electron microscope

7. Wellcome Institute SEM
Fly foot
Butterfly proboscis
Wellcome Institute SEM
How the SEM works
SEM Images

8. Magnification
The magnification of an object is how many times bigger the image is when compared to the original object
magnification =
actual size
size of image M I A
actual size =
magnification
size of image

9. Microscopic Units 1 millimetre = 1000 micrometres (µm)
1 micrometre = nanometres (nm)
Image
Actual
= 2 mm
= 8 mm
magnification =
actual size
size of image
= x 4

10. Image = 6mm ; Actual size = 20µm Magnification = ? Image = 6mm
Hint: keep the units the same !
magnification =
actual size
size of image
6000
= = x 300 20
Image = 6mm
Magnification = x 150
Actual size = ?
actual size =
magnification
size of image
6000
= = 40 µm
150

11. Resolution
X 6
Increasing magnification doesn’t always increase the resolution

12. Resolution is the ability to distinguish between two points – a lack of resolution means that the two points would appear as one
The resolving power of a microscope is related to the form of radiation being used to see the specimen
Using a light microscope objects 0.2µm or more apart can be seen separately

13. From coffee bean to carbon atom
Size is everything…
largest algal cell
leaf (thickness)
page
plant cell
animal cell
large bacterial cell
mitochondrion
cell membrane
µm (50mm)
500 µm (0.5mm)
100 µm (0.1mm)
40 µm (0.04mm)
20 µm (0.02mm)
5 µm (0.005mm)
1 µm (0.001mm)
7nm (0.007µm)
From coffee bean to carbon atom

26. =1mm
=1000µm
=0.5mm
=500µm
=0.1mm
=100µm
=0.04mm
=40µm
=0.02mm
=20µm
=0.005mm
=5µm

27. Feature
Light microscope
Electron microscope
Radiation
Max. resolution
Max. magnification
Lenses made of
Specimen
Support for specimen
Stains
Image
Cost

28. Light Electron Advantages: Disadvantages: Small, portable Very large
Preparation of material is relatively quick and simple
Lengthy preparation requiring skill and equipment
Material rarely distorted by preparation
Preparation of material may distort it
Natural colour can be observed
Images are black and white
Cheap to purchase and operate
Expensive to purchase and operate
Maximum magnification x1500
Magnification greater than
x with suitable resolution
Maximum resolution 200nm
Maximum resolution 0.1nm
Depth of field is restricted
Possible to investigate a greater depth of field

29. Drawing from the microscope

30. Drawing from the microscope

31. Microscope drawing Title/ Aspect(T.S. L.S ) Mag
Low Power Plans of tissues
Do not draw individual cells unless specifically told to do so.
No shading.
Ruled lines which do not cross.
Medium and High Power drawings
Show individual cells.
Only label cell organelles that are visible e.g. Cell wall, chromosomes, cytoplasm.
No shading etc. as above.

32. Gorgeous photomicrographs
Nikon Small World
Royal Microscopical Society;
Biannual competition