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Bio 234 > Microscopes and Cell Models > Flashcards

Microscopes and Cell Models Flashcards

1
Q

Smallest functional unit of life.

A

Cell

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2
Q
  • 1665
  • 1st to see dead cells
  • had microscope around 30X magnification
A

Robert Hooke

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3
Q
  • 1670s
  • made his own glass lens
  • microscope (which wasn’t a compound microscope) could maybe get up to 200X (SEE NOTES FOR DIAGRAM)
  • 1st to see living cells
A

Antoni van Leeuwenhoek

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4
Q

Cell Theory: Schleiden and Schwann 1839

-Has three main parts that are:

A
  1. All organisms consist of 1 or many cells.
  2. The cell is the basic unit of structure for all organisms.
  3. All cells come from pre-existing cells.
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5
Q

Eduard Strasburger and his “time-lapse” observations in 1880

A

He could track mitosis in plant cells

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6
Q

Goal is to decipher underlying principles that govern the structure and activity of the cell.

A

Microscopy

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7
Q

Two powers of microscopy:

A
  1. Magnification
    - lens (4x,10x,40x) and eye piece (4x, 10x)
  2. Resolution
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8
Q

Ability to make an object appear larger.

A

Magnification

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9
Q

Ability to distinguish two objects from each other (as being separate).

A

Resolution

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10
Q

Resolution

d=(0.5*wavelength)/n sin(theta)

A

d=distance

nsin(theta)=numerical aperture

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11
Q

Resolution Cont…
-The # found on the lens on the microscope.
-n sin(theta)
n=refractive index of the medium you’re using (ex. air, n=1; oil, n=1.5; H2O, n=1.3)
(theta)=1/2 angle of cone light (SEE NOTES FOR DIAGRAM)

A

Numerical aperture

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12
Q

To increase resolution, what parameters would you change when d=(0.5*wavelength)/n sin(theta)?
-Remember, smaller distance = greater resolution!

A
  1. Shorten wavelength (smaller numerator = smaller distance)
  2. Change n (larger denominator = smaller distance)
  3. Change cone of light by bringing objective closer to specimen (larger denominator = smaller distance)
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13
Q
  • Can see dead or alive cells
  • light path is at the bottom
  • Ocular lens (eye piece) usually 10x
  • Objective: 10x, 40x, 100x
  • Condenser (no magnification)
A

Light microscopy

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14
Q

Focuses light to a single area.

A

Condenser on microscope

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15
Q

Stained light micrographs

A
  • Staining kills specimen (fixing and staining procedures)

- There are controls in case staining makes something funny happen.

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16
Q

Variations of light microscopy to view living cells

A
  1. Bright-field
  2. Phase contrast
  3. Differential interference contrast (DIC)
17
Q

Basic light microscopy

A

Bright-field

18
Q

Can make shadows, give more topography of cell, and takes advantage of refractive indexes to cast shadows.

A

Phase contrast

19
Q

Shines light both below and on the side of specimen.

A

Differential interference contrast (DIC)

20
Q

Excitation and Emission

A

Fluorescence Microscopy

21
Q

Microscopy that requires one wavelength to excite sample and another wavelength to emit light.

  • Need fluorescence molecules (most common is GFP)
  • Good magnification, but poor resolution
A

Fluorescence Microscopy (SEE NOTES FOR DIAGRAM)

22
Q

Microscopy that uses a laser at a particular wavelength that will excite a sample (is a modification of florescence microscopy)
-Sample will emit light through the eye piece

A

Confocal microscopy

23
Q

Can focus on a particular plane of view, because it blocks out some of the light.

A

Pin Hole Aperture

24
Q

Moves to be able to look from layer to layer of specimen.

A

Motorized stage

25
Q

Microscopy that transmits electrons instead of light

-advantageous because as wavelength gets smaller, distance gets smaller and thus resolution is increased.

A

Transmission Electron Microscopy (TEM)

26
Q

TEM (and SEM) sample is dead because ___________.

A
  1. You’re using heavy metals with it

2. It’s in a vacuum

27
Q

Microscopy that looks at a sample’s topography (3D image) by scanning electrons at it.

A

Scanning Electron Microscopy (SEM)

28
Q

TEM:SEM as Bright-field:?

A

DIC (dissecting microscope)

29
Q

What types of cells are there?

A

Prokaryotes and Eukaryotes

30
Q

Advantageous characteristics of model organisms:

A
  • lots of offspring
  • fast lifecycle
  • small
  • easy to maintain
  • can genetically manipulate (can also manipulate behavior, & environment)
  • have a well-studied history
  • can live in culture, outside organism
  • ethically allowed to use
  • has genetic variation (can be severe or not)
31
Q

Is prokaryotic, single-celled, easy to maintain and manipulate, and can reproduce in 20min.

  • has circular DNA enclosed in a nucleoid region.
  • about 90% of what we know of DNA replication comes from this model organism
A

E. coli

32
Q

Model organism that is a fungus, eukaryotic, has quick replication (~30min), have a cell wall

A

Saccharomyces cerevisiae (“brewer’s yeast”)

33
Q

Model organism that is eukaryotic and can make 1000s of offspring in 8-10 weeks.
-Is a plant

A

Arabidopsis thaliana

34
Q

Model organism that is easily genetically manipulated, can grow fast (takes a few weeks), has lots of phenotypes to observe, and is eukaryotic.
-Studied this organism to find out about genes on chromosomes and linkage.

A

Drosophila melanogaster

35
Q

Model organism that is eukaryotic, develops like clock-work, and found everywhere.

  • has 959 body cells (we know exactly what every cell will do)
  • quintessential to apoptosis studies
A

Caenorhabditis elegans

36
Q

Model organism that is a vertebrate eukaryote, easy to maintain, takes only 3-4 months to develop, and can lay between 200-300 eggs a week
-The embryos are transparent

A

Danio rerio (zebra fish)

37
Q

Model organism that is a mammal.

  • Reproduces quickly (~4 months) and has larger litter sizes
  • easy to maintain
  • small
  • genetics are similar to humans’ genetics
  • are bred for a large variety of characteristics (domesticated animals) and are often inbred w/o much genetic variation to balance all the other varieties
A

Mus musculus (mouse)

38
Q

Model organism that scientists use to study fibroblasts, myoblasts, and epithelial cells among other things

A

Homo sapiens (humans)

Bio 234 (8 decks)

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