Lecture Set 1 Flashcards

1
Q

How do cells differ?

A

Morphology and physiology

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2
Q

Why do cells become differentiated?

A

Through development, even though cells all have same copies of DNA

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3
Q

What are the three tenets of the cell theory?

A

All organisms consist of one or more cells
Cell is the basic unit of structure for all organisms
All cells arise from preexisting cells

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4
Q

Discuss the difference between resolving power and limits of resolution

A

Resolving power = ability to distinguish objects as separate entities
Resolution = minimum distance between two objects such that they can still be recognized as separate

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5
Q

What determines resolution, how is it calculated?

A

Abbe equation
r= 0.61λ/nsin(α)
r = resolution, want it to be as small as possible
lambda = wavelength, want as small as possible
n = refractive index (change in velocity of light as medium changes) (want as large as possible)
alpha = angular aperture (half angle of the cone of light entering objective lens (want to be as close to 90 as possible)

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6
Q

How do you visualize cells with microscopy

A

1) fixate with preservative (formaldehyde) to complex with proteins/nucleic acids to maintain integrity of sample
2) Immobilize in wax
3) section –> cut thin slices
Can have light and fluorescent microscopy at same time b/c light deals with transmission, fluorescence relies on reflection

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7
Q

What are simple stains, what are they used for?

A

Used to produce contrast
basic –> positively charged, adds to negative charged molecules (eg crystal violet, methylene blue)
acidic –> negatively charged, adds to positive charges
(eg eosin, acid fuschsin)

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8
Q

What is Gram stain?

A

used to differentiate between gram + and gram - bacteria

uses certain dyes, gram + ends up blue, gram - ends up pink

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9
Q

What is fluorescence microscopy, what is it used for?

example of a fluorescent dye

A
used to identify specific molecules within cell (ex proteins)
use fluorochromes (ex DAPI --> binds to nucleus) that absorb and emit light
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10
Q

What is immunohistochemistry, what are the different types?

A

Attach fluorochrome to antibody that binds to specific proteins
Direct –> fluorochrome tag attachs to primary antibody bindign to protein
Indirect –> fluorochrome attaches to secondary antibody that binds to primary antibody binding to protein (signal heavily amplified)

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11
Q

What is confocal microscopy

A
Much more detailed/clear images
uses lasers of specific wavelengths
uses pinholes to eliminate other light
scanning one pixel at a time
uses photomultiplier tubes instead of cameras
can create 3D construction
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12
Q

What is deconvolution?

A

use of computer software to remove out of focus light from conventional microscopy to get to close to confocal clarity

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13
Q

What is an example of a native fluorochrome?

A

GFP –> occurs in jelly fish

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14
Q

What are the two types of electron microscopy?

A

TEM and SEM –> TEM = transmission, SEM = scanning, can only see surfaces in great detail

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