Microscopy

Question 1

What are the four types of microscopes?

Answer 1

Single, compound, fluorescent, electron

Question 2

Define the resolution of an optical microscope:

Answer 2

The shortest distance between two points on a specimen that can still be distinguished by the observer or camera system as separate entities.

Question 3

What are the advantages of a single microscope?

Answer 3

quick observations of specimens

Question 4

What are the disadvantages of the single microscope?

Answer 4

Very low resolution
Very limited magnification power

Question 5

What are the advantages of the compound microscope?

Answer 5

Reduced chromatic aberration
Increased magnification power
Exchangeable lenses

Question 6

What is chromatic aberration?

Answer 6

a common optical phenomenon that occurs when a lens cannot bring all wavelengths of light to a single converging point (so cannot focus) - so having this reduced is an advantage

Question 7

What are the disadvantages of a compound microscope?

Answer 7

resolution, intracellular structures not visible

Question 8

Advantages of fluorescent microscopes?

Answer 8

enables us to define sub cellular localisation of molecules conjugated with fluorescent dye

Question 9

Disadvantages of fluorescent microscopes?

Answer 9

Photobleaching
Autofluorescence

Question 10

Advantages of electron microscopes?

Answer 10

does not require molecular knowledge of the specimen under investigation
Very high resolution power

Question 11

Disadvantages of electron microscope?

Answer 11

Expensive
Laborious
Limited information acquired

Question 12

what does eosin (acidic - negatively charged) dye?

Answer 12

cytoplasmic components, membranes, fibres in cell - positively charged stuff)

Question 13

what does haematoxylin (basic - positive charge) stain?

Answer 13

DNA, RNA, nucleic acids (the negatively charged stuff)