Lecture Set 1 Flashcards
How do cells differ?
Morphology and physiology
Why do cells become differentiated?
Through development, even though cells all have same copies of DNA
What are the three tenets of the cell theory?
All organisms consist of one or more cells
Cell is the basic unit of structure for all organisms
All cells arise from preexisting cells
Discuss the difference between resolving power and limits of resolution
Resolving power = ability to distinguish objects as separate entities
Resolution = minimum distance between two objects such that they can still be recognized as separate
What determines resolution, how is it calculated?
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)
How do you visualize cells with microscopy
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
What are simple stains, what are they used for?
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)
What is Gram stain?
used to differentiate between gram + and gram - bacteria
uses certain dyes, gram + ends up blue, gram - ends up pink
What is fluorescence microscopy, what is it used for?
example of a fluorescent dye
used to identify specific molecules within cell (ex proteins) use fluorochromes (ex DAPI --> binds to nucleus) that absorb and emit light
What is immunohistochemistry, what are the different types?
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)
What is confocal microscopy
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
What is deconvolution?
use of computer software to remove out of focus light from conventional microscopy to get to close to confocal clarity
What is an example of a native fluorochrome?
GFP –> occurs in jelly fish
What are the two types of electron microscopy?
TEM and SEM –> TEM = transmission, SEM = scanning, can only see surfaces in great detail