Microscopy

Question 0

Resolution

Answer 0

-The ability to distinguish two separate points that are very close together

Question 1

Magnification

Answer 1

-The degree to which the size of an image is larger than the object itself

Question 2

The light microscope (4)

Answer 2

• Produces an image using a number of lenses
• Light passes from a bulb through the condenser lens and then the specimen
• Eyepiece has a magnification of x10
• There are four objective lenses x4 x10 x40 x100

Question 3

Advantages of the LM (4)

Answer 3

• Can magnify up to x1500
• Resolution of 200nm
• Can look at live specimens
• Small and cheap

Question 4

Staining

Answer 4

• Reference to any process that help to reveal or distinguish separate features. In light microscopy stains are colours or fluorescent dyes while in electron microscopy they’re metal salts or particles
  e. g. Gentian stains bacterial cell walls

Question 5

Sectioning

Answer 5

-Specimens are embedded in wax then sections are cut without distorting the structure. Useful for soft tissue e.g. Da brain

Question 6

TEM (transmission electron microscope) (4)

Answer 6

• Electron beam passes through thin prepared sample
• Pass through mediums of different density at different speeds, creating a contrasting image
• 2D image
• X500000 magnification

Question 7

SEM (scanning electron microscope) (2)

Answer 7

• Electrons are bounced off the sample

- 3D view

Question 8

Advantage of EM (3)

Answer 8

• Resolution is 0.1 nm
• Can produce detailed image of organelle structure
• 3D image can reveal detail of contour and cellular tissue arrangement

Question 9

Limitation of the EM (3)

Answer 9

• Samples have to be put in a vacuum as air deflects electrons
• Costs bare p’s
• You require high degrees of skill to use this