Microscopy

Question 1

Magnification

Answer 1

How many times larger the image is than the actual size of the object being viewed.

Question 2

Resolution

Answer 2

The ability to see individual objects as separate entities.

The Lowe the resolution, the better

Question 3

Magnification Formula

Answer 3

Magnification=Size of image/Actual size of object.

Question 4

Light microscope (normal)

Answer 4

• Low resolution of 0.2 micrometers (um).
• Maximum useful magnification of X1500.
• Used to observe whole cells.

Question 5

Laser scanning confocal microscopes.

Answer 5

• Causes dye to give off light.
• 3D image.
• Out of focus light is blocked, producing a clear image.
• Look at different depths in thick specimen.

Question 6

Transmission Electron Microscope (TEM)

Answer 6

• Maximum resolution of 0.0002um.
• Maximum magnification of X1,000,000
• Only 2D images.
• Used to observe organelles.

Question 7

Scanning electron microscope (SEM).

Answer 7

• Maximum resolution of 0.002 um
• Maximum magnification of X 500,000
• Produces 3D images.

Question 8

Reason for staining

Answer 8

• Staining increases contrast.

- Makes it easier to recognise different organelles.

Question 9

How to prepare a microscope slide

Answer 9

• Use tweezers to pick up the specimen and place it in the middle of a clean slide.
• Put a cover slip on top of the specimen.

Question 10

How to use a Light microscope.

Answer 10

• Clip the slide onto the stage.
• Select the objective lens with the lowest magnification.
• Use the Coarse adjustment knob to bring the stage up to just below the objective lens.
• Use the coarse adjustment knob to lower the stage, away from the objective lens until the image is in focus.
• Swap to an objective lens with a higher magnification to see the slide with a greater magnification.

Question 11

How to use an eyepiece graticule and a state micrometer.

Answer 11

• Line up the eyepiece graticule and the stage micrometer.
• Each division of the stage micrometer is 0.1mm long.
• At this magnification, 1 division of the stage micrometer=4.5 divisions on the eyepiece graticule.
• Division on the stage micrometer/divisions on the eyepiece graticule(0.1/4.5=0.022 mm)