MicroscopesMicroscopes

Object: To study the structure and function of Object: To study the structure and function of compound microscope.compound microscope.

MicroscopesMicroscopes MicroscopesMicroscopes are devices that produce magnified are devices that produce magnified

images of structures that are too small to see with the images of structures that are too small to see with the naked eye.naked eye.

Resolution Power: Resolution Power: The minimum distance of 0.2 The minimum distance of 0.2 m or m or 200 nm between the two particles200 nm between the two particles

MicroscopesMicroscopes

Light microscopes produce magnified images by Light microscopes produce magnified images by focusing visible light rays. focusing visible light rays.

Electron microscopes produce magnified images Electron microscopes produce magnified images by focusing beams of electrons.by focusing beams of electrons.

MicroscopesMicroscopes

Light MicroscopesLight Microscopes The most commonly used microscope is The most commonly used microscope is

the light microscope.the light microscope. Light microscopes produce clear images Light microscopes produce clear images

of objects at a magnification of about of objects at a magnification of about 1000 times.1000 times.

MicroscopesMicroscopes

Compound light microscopesCompound light microscopes allow light to allow light to pass through the specimen and use two lenses pass through the specimen and use two lenses to form an image.to form an image.

Light microscopesLight microscopes make it possible to study make it possible to study dead organisms and their parts, and to observe dead organisms and their parts, and to observe some small organisms and cells while they are some small organisms and cells while they are still alive.still alive.

Magnification Power (MP)Magnification Power (MP)::

MP = Power of eye piece X Power of object pieceMP = Power of eye piece X Power of object piece

The total magnification is the eye x objectiveThe total magnification is the eye x objective

 Object lenseye lensTotal

Magnification

Scanning4x10x40x

Low Power10x10x100x

High Power40x10x400x

Oil Lens100x10x1000x

Carrying a Microscope:

A B

Microscope Parts

A. OcularB. Body tubeC. Stage clipD. Revolving nose pieceE. ObjectiveF. ArmG. StageH. DiaphragmI. Lever to move stage clipJ. Course adjustmentK. Fine adjustmentL. Light sourceM. Base

MicroscopesMicroscopes

Electron Microscopes (EM):Electron Microscopes (EM): Light microscopesLight microscopes cannot produce clear images of cannot produce clear images of

objects smaller than objects smaller than 200 nm200 nm.. Resolution power for Resolution power for EMEM is about is about 0.5 nm0.5 nm.... To study even smaller objects, scientists use electron To study even smaller objects, scientists use electron

microscopes.microscopes.

MicroscopesMicroscopes

Electron microscopesElectron microscopes use beams of electrons, use beams of electrons, rather than light, to produce images.rather than light, to produce images.

The best electron microscopes can produce The best electron microscopes can produce images almost images almost 1000 times1000 times more detailed than more detailed than light microscopeslight microscopes can. can.

برغـوث برغـوث القططالقطط

Cat fleaCat flea

رأس رأس يراقة يراقة الذبابة الذبابة الزرقاءالزرقاء

خنفساء خنفساء الطحينالطحين

Red Flour Red Flour BeetleBeetle

head of a bedbug

عـث عـث الغـبـارالغـبـار

Dust miteDust mite

Wasp’s HeadWasp’s Head

Head of Head of Honey BeeHoney Bee

BedbugBedbug

Preparing SlidesPreparing Slides:: Using a pipet or Using a pipet or dropperdropper, add a drop of , add a drop of waterwater or or

another solvent to a clean microscope slide. Then, another solvent to a clean microscope slide. Then, place the place the specimenspecimen in the water. in the water.

Place the Place the edgeedge of a of a cover-slipcover-slip on the slide so that it on the slide so that it touches the edge of the water. touches the edge of the water.

Slowly lowerSlowly lower the cover-slip to the cover-slip to preventprevent the formation the formation of of air bubblesair bubbles..

1

2

3

Epithelial (cheek) Cells:

1- Nucleus 3 - Cytoplasm

2- Plasma membrane

Onion Cells PreparationOnion Cells Preparation

Obtaining sample of onion Obtaining sample of onion epidermisepidermis

Onion Cells:

1- Nucleus 3 - Cytoplasm

2- Cell Wall 4 - Plasma membrane

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2

3 4