Technologies used to study cells

Question 1

Explain how light microscope works

Answer 1

The light shines up through the specimen then travels through the objective and ocular lenses where it is refracted (bent) to create a magnified image.

Staining adds dyes which stain only certain cell components making them easier to view due to contrast.

Question 2

List field of views of light microscope

Answer 2

Field of view diameter: 40 x = 4.5 mm, 100 x =450 micrometer, 400 x = 150 micrometer.

Question 3

Explain how a confocal microscope works

Answer 3

Passes a highly focused laser through specimen resulting in high quality image of part of specimen, laser is moved repeatedly and images are sent to computer creating a 3D image of specimen

Question 4

Explain Electron Micorscope, 2 types

Answer 4

They use beams of electrons and electromagnets to make specimens look bigger.
Electron gun shoots a beam of electrons (controlled by electromagnets) towards the specimen, when it hits the specimen the beam scatters which is dependent on the specimen.
The scattering is detected and sent to a computer which creates an image.

Question 5

SEM vs TEM

Answer 5

Transmission - electrons are transmitted through specimens producing a 2D image, resolution is 2nm, magnified up to 1 500 000 times.

Scanning - bombards solid specimens with beams of electrons which causes secondary electrons to be emitted from the surface layer (due to layer of gold) of the specimen, beam focuses on one part at time and scans the whole thing. 10nm resolution (worse) but gives 3D images of surfaces.

Question 6

Compare light and electron

Answer 6

Light: less magnification, cheaper, easily trainable, low resolution, view living cells, see colour
Electron: high magnification, expensive, high training, high resolution, view dead cells, no colour