Micro Test 1 : Chapter 2 Microscopy And Visulizing Cells Flashcards
Visible light
Electromagnetic energy waves constrained with certain range of wavelengths that we can see
Reflection
Light bouncing off a surface
Absorbance
When energy is captured by the reflecting material
Transmittance
The process of light traveling through a material
Transparency and opacity
The relative ability and inability to transmit light
Interference
When light waves interact with each other
Diffraction
The bending or scattering of light when it strikes a small object or passes through an opening
Lenses how they work
Light waves can change speed when entering a new medium which can cause them to change direction
Refractive index
The degree to which a medium changed the speed of light
Lenses
Lens like prism - bends
Convex lense - bends light inward to a cone where light rays meet at a focal point
Concave lens - scatters light from a focal point outwards
Light is focused before entering eye where it is focused again resulting in a enlarged image
Florescence
when a substance absorbs light of one higher wavelength and uses that energy to emit light at another lower wavelength
Magnification
Ability of a lens to enlarge the image
Resolution
The ability to tell two different objects apart when views through a lens
Contrast
The ability to differentiate an object from the background
Microscopes types
Simple (single lens)
Or
Compound (multiple lenses)
Most Common Microscope
Bright field
Has a lightened background with most light being directed at the specimen
Darkfeild microscope
Provides a dark background and lights up specimens
Florescence microscopy
Utilizes fluorescent molecules (fluorochromes) to tag structures
Light contains a excitatory wavelength lights up fluorochromes
Confocal microscopy
Similar to fluorescent microscopy uses fluorochromes and laser to illuminate them
Creates 3D images
Electron microscopy
Uses electron beam to illuminate images
Allows to see much smaller molecules
TEM (tunneling) penetrates to show internal structure
SEM (scanning) renders 3D images
Scanning Probe microscopy
Uses very fine and sharp prone that passes over object
Visualize 100,000,000x mag visualize molecules and larger atoms
Bacteria seen with…
Bright field microscope through wet or heat fixed mount
Stains are often used to see transparent cells
Stains
Either basic or acidic (opposites attract)
Basic stain + charge called positive stain attarcts to - cells
Acidic stain - charge called negative stain attracts to + cells
Simple stain
One Dyes all cells in a sample the same color
Differential stain
Uses two or more dyes for diff cells to see their unique properties
Gram stain
A differential stain that is one of the most common staining techniques used
Gram stain invented by…
Hans Cristian Gram 1884
Distinguishes between bacteria with tow diff cell wall motifs
Gram negative bacteria def
Bacterium loses the primary stain in the presence of decolorizer
Gram pos bacterium def
Retains primary stain in the presence of decolorizer
Primary stain
Crystal violet used with a mordant or hardening agent (grams iodine) causes primary stain to stick to the bacterial wall
Decolorizer
Ethanol or ethanol & acetone mix
Secondary stain
Or counter stain is safranin
Bacterial walls
Thick or gram positive bacteria has thick walls made of peptidoglycan
Thin walls lose color and become transparent (light pink because safranin)
Acid fast stain
Used for bacteria with waxy hydrophobic cell walls like mycobacterium
AFB+ one that retains the primary stain with presence of an acidified decolorizor (red)
AFB- one loses primary stain or acidic decolorizer and use of secondary stain methane blue (light blue)
Capsule stain
Some cells secrete protective gel around them called glycocalyx
With capsule stain we stain the surrounding background
Virulence factor
Ability to form a capsule around bacterial material aids in bacterium causing disease
Endospores
Some bacteria had ability to package up material into a hard durable endospore that is resistance to heat and chemicals can survive a long time and can regerminate
Flagella stain
Some bacteria archaea and eukaryotes have tail like structures too thin to see with optimal scope
Layers of dye added to thicken flangella to be able to see
Morphology
Cell shape including appendages
Aggregate
How members of a colonial colony associate with each other
