Topic 1 Microscopes and Microscopy

Light Microscopes  How do they work?  Optical magnification  Images pass through a lens or a series of lenses  Properties of specimens?  Used to identify…  Composition  Prokaryote vs Eukaryote  Maximum magnification?  Determined by multiplying ocular lens and objective lens  How do they work?  Optical magnification  Images pass through a lens or a series of lenses  Properties of specimens?  Used to identify…  Composition  Prokaryote vs Eukaryote  Maximum magnification?  Determined by multiplying ocular lens and objective lens OBJ 1, 2

Differential interference-contrast Optical microscopes that use complex lighting to give contrast to transparent objects

Fluorescence confocal Microscopy technique involving a dye that fluoresces when excited by a laser beam. Use to show differing contrasts of specimens. Requires very special equipment

Magnification vs. Resolution  Magnification - increase in size  Resolution - measure of clarity  Ability to show two objects as separate  Human eye has limit of 0.1 mm  Light microscope has limit of 0.2 micrometer  Magnification - increase in size  Resolution - measure of clarity  Ability to show two objects as separate  Human eye has limit of 0.1 mm  Light microscope has limit of 0.2 micrometer OBJ 1

Magnification OBJ 1

Resolution OBJ 1

Field of view  Area you can see  circular  Measuring size  Using a clear ruler…  Measure the size of your field of view  Estimate the size of objects  4.5 mm  Area you can see  circular  Measuring size  Using a clear ruler…  Measure the size of your field of view  Estimate the size of objects  4.5 mm OBJ 3

Electron Microscopes  Use a beam of electrons instead of light  100X better resolution than light  1 to 5 nanometers!  SEM and TEM  Use a beam of electrons instead of light  100X better resolution than light  1 to 5 nanometers!  SEM and TEM OBJ 2

Transmission Electron Microscope (TEM) Spinach Cell Chloroplast OBJ 2 Electrons pass through the specimen

TEM Golgi Apparatus OBJ 2

TEM Red Blood Cell in a capillary of the pancreas OBJ 2

Scanning Electron Microscope (SEM) OBJ 2 Focused beam of electrons are scanned over the specimen.

SEM OBJ 2 Fish gills

SEM OBJ 2 Insect “foot”

SEM OBJ 2 Your worst nightmare