MolBio16 - 17

Question 1

What is our optical near point?

Answer 1

The least distance of distinct vision - around 250mm

Question 2

When were cells first observed and named?

Answer 2

17th Century - Antonie van Leeuwenhoek

Question 3

What was the next step after Leeuwenhoek’s simple microscope?

Answer 3

Compound microscope - 30x

Question 4

What is a transmitted microscope for?

Answer 4

Viewing tissues and cells stained with dyes

Question 5

What is phase contrast and DIC microscopy for?

Answer 5

Viewing unstained tissues and cells

Question 6

What is a reflected microscope for?

Answer 6

Viewing fluorescent dyes and proteins in cells and tissues

Question 7

What are the three requirements for microscopy?

Answer 7

Resolving power, contrast, magnification

Question 8

What is resolving power?

Answer 8

Ability to carry information about fine detail in the specimen to the image

Question 9

What is contrast?

Answer 9

Difference in the image between features and their surroundings

Question 10

What is magnification?

Answer 10

Ability to make image large enough for the eye to appreciate the resolved detail

Question 11

Describe a transmitted light microscope

Answer 11

Light passes through specimen, so tissue must not be too thick or opaque

Question 12

What are the advantages of fluorescence microscopy?

Answer 12

Very high contrast, wide range of fluorescent markers, sensitive cameras can collect weak signals

Question 13

What is transmitted electron microscopy for?

Answer 13

Viewing internal detail in a very thin slice

Question 14

What is scanning/reflected electron microscopy for?

Answer 14

Viewing surface

Question 15

What are the lenses in electron microscopy?

Answer 15

Magnetic coils

Question 16

How does SEM work?

Answer 16

Sample coated with gold, electrons reflect from surface

Question 17

How does TEM work?

Answer 17

Tissues are sectioned and impregnated with heavy metals, electrons scatter when hitting large atoms, giving more contrast