Introduction to the MicroscopeCarePartsFocusing

Always carry with 2 handsOnly use lens paper for cleaningAlways store coveredKeep objects clear of desk and cords

Proper ProceduresCarry the microscope with one hand under the base while grasping the arm with the other handPlace microscope ~5 inches from the edge of the table

Be careful of the cord when moving around the lab tables!!

Proper Procedures3. Rotate the nosepiece to obtain the proper objective lens Make sure the lens clicks into place!!

4. Look through the eyepiece and switch on the lampThis is your field of view!

Proper Procedures5. Place slide on stage, center specimen over stage 6. Locate specimen on low power using coarse adjustment 7. Carefully switch to medium or high power8. Focus image with fine adjustmentAvoid damaging slide! Do not use course adjustment with high power!

EyepieceBody TubeRevolving NosepieceArmObjective LensStageStage ClipsCoarse FocusFine FocusBaseDiaphragmLight

*

MicroscopeOne or more lense that makes an enlarged image of an object.

Place the Slide on the MicroscopeUse Stage Clips Click Nosepiece to the lowest (shortest) settingLook into the EyepieceUse the Coarse Focus

Follow steps to focus using low powerClick the nosepiece to the longest objectiveDo NOT use the Coarse Focusing KnobUse the Fine Focus Knob to bring the slideWhat can you find on your slide?

Where does it belong?If I am studying Bacillus subtillis, how would I classify this organism as a taxonomist?

Comparison of Eukaryotic and Prokaryotic cells

SimpleCompoundStereoscopicElectron

Simple MicroscopeSimilar to a magnifying glass and has only one lense.

Compound MicroscopeLets light pass through an object and then through two or more lenses.

Stereoscopic MicroscopeGives a three dimensional view of an object. (Examples: insects and leaves)

Electron MicroscopeUses a magnetic field to bend beams of electrons; instead of using lenses to bend beams of light.

Optical Microscopy

*The Light Microscopemany typesbright-field microscopedark-field microscopephase-contrast microscopefluorescence microscopesare compound microscopesimage formed by action of 2 lenses

1. Bright Field MicroscopyDark object on bright backgroundLight- solid column of lightHotDifferent densities not distinguishedResolving power - .2 micrometersStaining takes advantage of chemical differences

*The Bright-Field Microscopeproduces a dark image against a brighter backgroundtotal magnification product of the magnifications of the ocular lens and the objective lens

2. Dark Field MicroscopyBright object on dark backgroundLight- Hollow cone of light Only diffracted light seenResolving power - .2 micrometersGood for viewing in the natural environment

*The Dark-Field Microscopeproduces a bright image of the object against a dark backgroundused to observe living, unstained preparations

3. Phase Contrast MicroscopyCombines bright and dark field microscopyDiffracted light from hollow cone passed through special objective lensResolving power - .2 micrometersGood for viewing living specimens

*The Phase-Contrast Microscopeenhances the contrast between intracellular structures having slight differences in refractive indexexcellent way to observe living cells

Bright Field Dark FieldPhase Contrast

4. Fluorescent MicroscopyBright object on dark backgroundLight- UV light combined with fluorescent dyeBacteria will fluoresce different colorsResolving power -

*The Fluorescence Microscopeexposes specimen to ultraviolet, violet, or blue lightspecimens usually stained with fluorochromesshows a bright image of the object resulting from the fluorescent light emitted by the specimen

Fluorescent Microscopy

3-*

Electron Microscopy

1. Electron MicroscopyTransmissionResolving power 0.0001micrometersScanning3D image

Mycobacterium tuberculosis

Scanning electron microscope image (prepared using the critical point drying technique) showing bacteria distributed over the surface of shredded lettuce leaf at the end of its shelf life (image prepared by Dr Mary Parker, IFR).

Scanning Electron MicroscopeStreptococcusBacteriaPenicillium

Transmission Electron MicroscopyHerpes virus on Oyster flat

*primary stainmordantcounterstaindecolorizationpositivenegative

*The Transmission Electron Microscopeelectrons scatter when they pass through thin sections of a specimentransmitted electrons (those that do not scatter) are used to produce imagedenser regions in specimen, scatter more electrons and appear darker

*The Scanning Electron Microscopeuses electrons reflected from the surface of a specimen to create imageproduces a 3-dimensional image of specimens surface features

EyepieceArmStageCourse adjustmentFine adjustmentBaseLets Review!12.13.Body tubeNosepieceLow powerHigh powerStage clipsDiaphragmLight sourceMedium power

Microscope Self Quiz

So Lets ReviewBody tubeEyepieceNosepieceLow powerMedium powerHigh powerStage clipsDiaphragmLight sourceArmStageCourse adjustmentFine adjustmentBaseLets Review!

*Students will have their microscopes out, for reference as we go through each of the steps. As an introduction, students will be asked what kinds of things they can do with this tool.*Teacher demonstrates how to hold the microscope, where the lens paper is located and how to use it. Students will be invited to turn the knobs and observe the stage as it moves up and down. Teacher will demonstrate how to store the microscope. *This is the exact version of the microscope used in class. Students will be identifying the parts on the microscopes at their desks as we go along and what their functions are. *Give students a slide from the common things set, each student will practice focusing and changing objectives.*Have students exchange slides so they can look at different things, walk them through using the high power objective to focus slides. Emphasize not using the coarse objective during this process, as it will crack the slides.*******