Download Introduction to Microbiology - Lecture Notes | BIOL 2230 and more Study notes Microbiology in PDF only on Docsity! Microbiology 9/1/11 Microscopy: 3 Key Features for Success: 1) magnify 2) contrast (staining) 3) resolution: bring able to distinguish two points as two separate points; about ½ wavelength of light; better resolution with a shorter wavelength High energy, short wavelength low energy, long wavelength With 400 nm of light, objects as small as 200 nm can be resolved. The visible spectrum of radiation is ROYGBIV; This is why there is an indigo filter that the light goes through on a microscrope – that creates the most visibility, violet would start to put some details past visibility Types of Microscopes: Brightfield: normal microscope; the field of vision if bright, so a stain must be used = dead organism Dark Field: specimen receives all of the light = no light needed, so living specimens can be viewed Phase-contrast: Light in its different phases goes through a series of metal rings and is forced into one “phase” that provides contrast; can use live specimens Fluorescence: specimen is coated with fluorescent dye, which turns into UV light (which is too short a wavelength to see but it excites the electrons on the cell to emit visible light) that’s emitted in the visible range so you can see what’s going on in the cell; down side is that this method is harmful to your eyes. Electron Microscopes: electrons are the light source; can see best with electron microscopes o Transmission: electrons go through an ultra-thin section in the specimen and the image is collected beneath o Scanning: used for thicken specimens, like hair; electrons bounce off the specimen, and that is the image that is collected Eukaryotic vs. Prokaryotic Cell Biology Classification: o 3 Domains: bacteria, archaea (one-celled, can survive acid), eukarya o 5 Kingdoms: monera (only prokaryotic kingdom, simpler than eukaryotic kingdoms because they don’t have organelles), protista, fungi, plantae, animalia Eukaryotic Organelles: Membrane-bound entities that carry out some specific function
