Biology 1002B Study Guide - Quiz Guide: Lysosome, Vacuole, Centriole
Microscopy
- ZZTwo types: Light or electron. Differs by source of illumination (light/electron).
- Magnification: Ratio of (Size of object viewed in microscope):(Real size)
- Resolution: Min. distance required for two points to be distinguished under microscope
-Depends on: Wavelength of light/electron (shorter the better)
-Electrons have shorter wavelength and provide better resolution
- Light Microscopy
• Bright Field Microscopy:
o -Light passes directly through specimen
o Staining with dye may be used to contrast internal structures - may kill the
cell.
• Dark Field Microscopy:
o Light illuminates specimen at an angle.
o Light scattered by specimen reaches viewing lens
o Produces bright image of cell against dark background
• Phase-Contrast Microscopy:
o Diff. densities within specimen causes refraction in light.
o Refraction causes contrast revealing invisible structures.
• Nomarski (Differential Interference Contrast):
o Same as phase-contrast but with special lenses creating 3D image.
• Fluorescence Microscopy:
-Specific structures or molecules are stained with fluorescent dyes.
o Structures or molecules fluoresce when viewed with UV light.
• Confocal Laser Scanning Microscopy:
o Sharpest 3D image of light microscopy.
o Laser scan fluorescent stained specimens.
o Computer used to view individual plans throughout the cell.
-Electron Microscope
Transmission Electron Microscope (TEM):
• Beam of electron focused on thin section of specimen
• Electrons that pass through from image, structures scattering electrons appear dark.
• Staining can be used to highlight certain structures/molecules.
Scanning Electron Microscope (SEM):
• Electron scanned across whole specimen.
- Electron excited on the specimen’s surface are converted into 3D image.
Higher Organization
-Cells with similar characteristics group together into tissues
-Tissues→ Organs→ Organ Systems→ Organism
Cell Types: Prokaryote VS. Eukaryote
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Document Summary
Magnification: ratio of (size of object viewed in microscope):(real size) Resolution: min. distance required for two points to be distinguished under microscope. Depends on: wavelength of light/electron (shorter the better) Electrons have shorter wavelength and provide better resolution. Transmission electron microscope (tem): beam of electron focused on thin section of specimen, electrons that pass through from image, structures scattering electrons appear dark, staining can be used to highlight certain structures/molecules. Scanning electron microscope (sem): electron scanned across whole specimen. Electron excited on the specimen"s surface are converted into 3d image. Cells with similar characteristics group together into tissues. Gene sequences do not resemble any domains of life. No nuclear membrane: genetic info stored in nucleoid. Used for locomotion and provides extra layer of protection. Er: divided into smooth er and rough er. Rigid cell wall (due to cellulose) with plasmodesmata (pore)
