Topic 2 - Microscopy

Question 1

Magnification

Answer 1

How much bigger an object is that the original

Question 2

Resolution

Answer 2

How far apart 2 points can be before theyre seen as one

Question 3

Types of microscopes

4

Answer 3

• optical
• transmission electron
• scanning electron
• ultra structure

Question 4

Types of microscopes

Optical

Answer 4

• beam of electron through object
• objective lens + eye piece magnify sample

mag = 1500x res =200nm

Question 5

Types of microscopes

transmission electron

Answer 5

-beam of electrons through sample / 2d image
-thin sample used

mag = 50,000x res=0.1nm

Question 6

Types of microscopes

Scanning electron

Answer 6

• beam of electrons back and forth over surface of object / 3D

mag= 50,000x res=0.1nm

Question 7

Types of microscopes

Ultra structure

Answer 7

structures only visible through TEM
- electron microscopes show more due to their shorter wavelengths, giving higher resolution

Question 8

Types of microscopes

why is staining required for samples

Answer 8

• provides contrast btwn organelles and cytoplasm
• allowing structures to be observed

Question 9

Types of microscopes

what type of stain used for electron microscopes and why?

Answer 9

-heavy metals
- electrons to reflect

Question 10

Types of microscopes

what stain is used for light microscopes?

Answer 10

• methylene blue
• acetocarmine
• haematoxylin

Question 11

1 advantage of electron microscopes

Answer 11

• higher resolution and magnification

Question 12

3 disadvantages to electron microscopes

Answer 12

• very expesive + not portable
• sample must be placed in vacuum, can’t magnify living things
• produces only black and white images