Intro + Microscopy Flashcards
what are the 3 divisions of the living world
bacteria, archaea} (prokaryotes), eukaryotes
what divides the 3 branches?
the distance between them is based on the differences in their nucleotide sequences as there is vast variability
what are the characteristics of eukaryotes?
- have a nucleus
- 1000x larger by volume, - a phospholipid bilayer membrane (have an inner and outer membrane)
- intercellular communciation
- high degree of organization and compartmentalization
- made of 70% H2O, ATP required
- chemical comp: sugars, fatty acids, amino acids, nucleotides
what is the average size of a eukaryote
10-100 microm
what about water’s structure makes it important?
- covalent bonds that make it weak enough to be a universal solvent
- weak hydrogen bonds ensure different H2O molecules
- can be a solid liquid or gas
- can support a lot of reactions
- hydrophobic effect that causes the cell membrane to function
What are some characteristics of the plasma membrane?
- amphipathic (hydrophobic/philic)
- arranged in oil and water
- phospholipids arrange in a bilayer
- permeable, has certain membrane proteins that allow for exchange of important ions, proteins, etc that are not permeable
list the types of microscopy
light and electron microscopy
name the different types of light microscopy?
conventional, fluorescence, confocal, two-photon
what is the range of electron microscopy?
0.1nm - 1.1mm
what is the range of light microscopy?
10nm - 1.1mm
what is the range of naked eye?
100 microm - 1cm
how do light microscopes work and what are they used for?
utilizes: basic light path
used for: live or fixed cells and tissue
what is the use of a upright vs inverted microscope?
upright microscope: tissues
inverted microscope: isolated cells
what is the structure of a light microscope?
eye > eyepiece > tube lens > objective > specimen > condenser > iris diaphragm > light source
name the type of conventional light microscopy?
bright field, phase contrast, differential interference contrast, dark field
how does bright field microscopy work?
Light passes through the sample, and the image is formed based on light absorption, scattering, or transmission.
how does phase contrast microscopy work?
It converts differences in the refractive index aka phase differences (light-bending properties) of transparent samples into differences in light intensity.
wave properties of light can be exploited. in unstained cells, a phase shift will occur as light travels through the cell. phase alignment is related to increased brightness; if not aligned, decreased brightness. observable with phase contrast
what is differential interference contrast microscopy?
- similar principles as with phase contrast
- polarized light is separated and recombined
- more definition
what is dark field microscopy?
lateral light source shows
only scattered light.
what’s the structure of phase contrast microscopy?
light source > annular diaphragm > condenser lens > direct light (phase unaltered by specimen) > phase plate > image plane
what’s the structure of dic?
light source > polarizer > wollaston prism > conenser lens > 2 beams of plane-polarized light separated by the prism below > stage > specimen > objective lens > wollaston prism > analyzer (rotated 90* with respect to polarizer) > image plane
list some facts about fluorescence microscopy
- detects specific molecules and ions
- works as it atomically abrobs a photon, then emits it at a specific, longer wavelength so a light signal is detected
- fluorescent molecules are used to emit certain lights; each has special characteristics from each dye and molecule
What kinds of dyes and molecules are used for fluorescence microscopy?
DAPI, GFP (green fluorescent protein), FITC (dye)
what’s the structure of a fluorescence microscope?
looks similar to a light microscope
light source (high energy lamp) > first barrier filter (reduces unwanted wavelengths) > beam-splitting mirror uses chromophores to excite wavelengths > second barrier filter (reduces unwanted wavelengths, transmitting wavelengths