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Biology > Chapter 1: Microscopy > Flashcards

Chapter 1: Microscopy Flashcards

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1
Q

What is used to produce ultra-thin slices of specimen to observe under a microscope? what are these clices called?

A

A microtome.

Sections.

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2
Q

What was the theory of spontaneous generation? Why was it proposed and believed?

A

That life could be produced from non living matter. Proposed from the existence of life in seemingly sterile conditions.

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3
Q

How was spontaneous generation disproved?

A

Louis Pasteur’s swan-neck experiment, demonstrated how bacteria only grew in sterile conditions after being exposed to air (which contained bacteria)

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4
Q

how do light microscopes work?

A

light from a mirror is reflected through a specimen into the objective lens, which magnifies it. hen it is further magnified by the eyepiece lens

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5
Q

advantage of compound microscopes over simple ones?

A

reduced chromatic aberration/distortion

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6
Q

advantages of light microscopes?

A
  • can observe living specimens
  • no harsh chemicals involved
  • easy to set up
  • inexpensive
  • can see in colour or if using a stain
  • vacuum not required
  • sample preparation doesn’t lead to distortion
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7
Q

disadvantages of light microscopes?

A
  • low magnification
  • low resolution
  • cannot see ribosomes
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8
Q

magnification/resolution of LM

A 
M = 2000
R = 200 nm
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9
Q

how does a laser scanning confocal microscope work?

A

a single spot of laser light of high energy illuminates chemical dyes on a specimen, causing them to fluoresce.

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10
Q

what is fluorescence?

A

absorption and re-radiation of light to a longer wavelength and lower energy / thus fluoresce

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11
Q

advantages of LSCM

A
  • high depth selectivity and so can veiw whole cells
  • can see living specimens
    can track molecules
  • high secolution than LM
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12
Q

disadvantages of LSCM?

A
  • more expensive

- more complex

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13
Q

how can we get 3D images from LSCM?

A

by using light from more than one focal point

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14
Q

why is a laser used instead of light in LSCM?

A

higher intensities, improves illumination, and higher energy, so light re-emmitted is fluorescent

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15
Q

define the term relsolution (microscopy)

A

the ability of a microscope to distinguish between two points on a specimen / the smallest interval measurable by a microscope

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16
Q

define magnification

A

how much an image can be magnified from the original

17
Q

uses of LSCM?

A
  • used to observe fungal filaments with in the cornea
  • new drugs
  • virtual biopsies
18
Q

how does a TEM work?

A
  • beam of electrons fired from cathode and focused using magnets
  • ransmitted through a specimen and focused
  • form image
19
Q

advantages of TEM?

A
  • can see details inside cells
20
Q

disadvantages of TEM?

A
  • general EM dis
21
Q

magnification/resolution fo TEM

A 
M = 500,000
R = 0.5 nm
22
Q

how does a SEM work?

A
  • beam of electrons fired form cathode and focused by magnets
  • electrons sent across surface of specimen
  • secondary electrons reflected and collected
23
Q

advantages of SEM

A
  • 3D images produced
24
Q

disadvantages of SEM

A
  • specimen must be dehydrated and metallic salt stains placed
  • sample preparation causes distortion
  • lower resolution
25
Q

magnification/resolution of SEM

A 
M = 200,000
R = 3-10 nm
26
Q

general disadvantages of EM ?

A
  • grayscale images, digital false colour can be added
  • generally dead
  • expensive
  • complex, need skill/training
  • vacuum required
  • ## sample preparation may cause distortion of image
27
Q

magnification equaiton?

A

M=I/A

28
Q

purpose of differential staining?

A
  • different organelles absorb different amounts of stain

- thus we can differentiate between them

29
Q

all purpose stain (stains all)

A

methylene blue

30
Q

stain that binds to DNA and stains chromosomes what colour

A
  • acetic orcein

- dark red

31
Q

stains cytoplasm?

A
  • eosin
32
Q

stains lipids?

A
  • sudan red
33
Q

stains cellulose in plant walls WHAT COLOUR and starch granules WHAT COLOUR

A
  • iodine in potassium iodide
  • culluose walls yellow
  • starch granules blue/black: violet under microscope
34
Q

what is done by experts to specimens before use in labs?

A
  • specimens dehydrated
  • embedded in wax to prevent distortion during slicing
  • sliced using microtomes (knives) to make VERY THIN slices called SECTIONS
  • fixing using formaldehyde to stop specimens in near natural state
35
Q

how to you use/calibrate an eyepeice graticule using a stage micrometer?

A
  • clip in stage micrometer
  • place EPG into eyepeice lens
  • align, measure from 2 intervals
  • MATHSSSS
36
Q

types of mounts?

types of slides?

A
  • wet mount
  • temporary mount
  • dry mount
    + smear slide
    + squash slide
37
Q

how is each mount/slide prepared?

A
  • dry: specimen sliced using microtome
  • wet: specimen immersed in liquid, cover slip at 45
  • temporary mount: in liquid evaporates, cover slip
  • squash: soft specimen, wet mount squashed using cover slip
  • smear: edge of cover slip used to smear, dropped at 45

Biology (25 decks)

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