More microscopy- 2.3 (3)

Question 1

What is an artefact?

Answer 1

a visible structural detail caused by processing the specimen and not a feature of the specimen

Question 2

In which two types of microscopes do artefacts appear in?

Answer 2

light microscopes and electron microscopy

Question 3

The bubbles that get trapped under the cover slip as you prepare a slide…

Answer 3

for light microscopy are artefacts

Question 4

What is inevitable when preparing specimens for electron microscopy?

Answer 4

the changes in the ultrastructure of cells during the processing that the samples must undergo

Question 5

What are artefacts seen as? - the loss of…

Answer 5

continuity in membranes

Question 6

What are artefacts seen as? - distortion of…

Answer 6

organelles

Question 7

What are artefacts seen as? - empty spaces in the…

Answer 7

cytoplasm of cells

Question 8

What does experience enable scientists to distinguish?

Answer 8

between a artefact and a true structure

Question 9

What can cause much discussion and controversy?

Answer 9

identifying artefacts in microscopy preparation

Question 10

What was mesosome given as a name to?

Answer 10

invaginations (inward foldings) of cell membranes that were observed

Question 11

What were mesosomes observed using?

Answer 11

electron microscopes after bacterial specimens had been chemically fixed

Question 12

Were mesosomes thought to be a normal structure, or organelle, found within prokaryotes?

Answer 12

yes

Question 13

The large surface area of the folded membrane was considered to be an…

Answer 13

important site for the process of oxidative phosphorylation

Question 14

When specimens were fixed by the more recently developed, non-chemical technique called cryofixation, the…

Answer 14

mesosomes were no longer visible

Question 15

What is now widely thought of mesosomes?

Answer 15

majority of mesosomes observed are actually artefacts

Question 16

What are mesosomes produced by?

Answer 16

chemicals used in the fixation process in electron microscopy preparation

Question 17

Are there still a number of scientists who believe that some species of bacteria do have mesosomes as part of their normal structure?

Answer 17

yes

Question 18

What makes it a good example of how the scientific community accepted an idea based on the evidence available at the time?

Answer 18

as techniques improved and more evidence became available, the collective knowledge and, understanding developed, and changed.

Question 19

What can new evidence provide?

Answer 19

either further support for a theory or disprove an earlier theory

Question 20

What is constantly developing?

Answer 20

scientific knowledge

Question 21

What has also continued to develop?

Answer 21

light microscopy

Question 22

What do some of the latest technology produce?

Answer 22

images that are very different from electron micrographs but are just as useful

Question 23

What is the function of conventional optical microscopes?

Answer 23

they use visible light to illuminate specimens and a lens to produce a magnified image

Question 24

In fluorescent microscopes, what is used to illuminate a specimen that has been treated with a fluorescent chemical / dye?

Answer 24

a higher light intensity

Question 25

What is fluorescence?

Answer 25

it is the absorption and re-radiation of light

Question 26

What is used to produce a magnified image in laser scanning confocal microscopy?

Answer 26

light of a longer wavelength and lower energy is emitted and used

Question 27

What moves a single spot of focused light across a specimen?

Answer 27

a laser scanning confocal microscope

Question 28

What does the movement of a single spot of focused light across a specimen cause?

Answer 28

fluorescence from the components labelled with a dye

Question 29

What is the emitted light from the specimen filtered through?

Answer 29

a pinhole aperture

Question 30

What is only detected?

Answer 30

light radiated from very close to the focal plane

Question 31

What is the focal plane?

Answer 31

the distance that gives the sharpest focus