ENH 222 Lecture Notes - Lecture 2: Clostridium, Basal Body, Vacuole

• School: Ryerson University
• Department: Environmental Health
• Course: ENH 222
• Professor: Melissa Moos

Document Summary

Units of measurement: microorganisms are measured in micrometers (cid:523) m(cid:524) and nanometers (nm) (cid:883) m = (cid:883)(cid:882)-6 m = 10-3 mm (cid:883)(cid:882)(cid:882)(cid:882) nm = (cid:883) m (cid:882). (cid:882)(cid:882)(cid:883) m = (cid:883) nm. Microscopic resolution between (cid:884) points (cid:882). (cid:884) mm. Immersion oil: shorter light wavelengths - greater resolution, refractive index: light- bending ability of medium, air: light bends so much that it misses small high- magnification lens. Immersion oil: same refractive index as glass: used to keep light from bending. same effect as increasing objective lens diameter improves resolving power of lens. Brightfield illumination: regular condenser & light illumination, refracted light from specimen enters objective lens. Internal structures visible: dark objects against a bright background, outline of external covering, unstained samples difficult to see, poor background contrast, used for stained samples. Darkfield illumination: darkfield condenser: opaque disc blocks out centre of light beam, light refracted off the specimen enters the objective lens.