Microscopes and Microscopes and Basic MeasurementBasic Measurement

How are they used to study How are they used to study the living environment?the living environment?

Measuring and UnitsMeasuring and Units

Use a standardized system (metric Use a standardized system (metric system)system)– Meters = lengthMeters = length– Gram = massGram = mass– Liter = volumeLiter = volume

Why Use Metric?Why Use Metric?

Base 10 systemBase 10 system Easier to convert unitsEasier to convert units Simply multiply or divide by 10 to Simply multiply or divide by 10 to

change unitchange unit

PrefixesPrefixes

Used to show smaller or larger Used to show smaller or larger measurementsmeasurements– MegaMega– KiloKilo– HectoHecto– DekaDeka– DeciDeci– CentiCenti– MilliMilli– MicroMicro– NanoNano

Important Unit for Important Unit for MicroscopesMicroscopes

Micrometers (microns) = µmMicrometers (microns) = µm 1/1000th of a millimeter1/1000th of a millimeter 1000 micrometers = 1 mm1000 micrometers = 1 mm

How Big How Big is a is a Micron?Micron?

Early MicroscopesEarly Microscopes

Anton Van Leeuwenhoek (1670’s)Anton Van Leeuwenhoek (1670’s) First to see and describe single First to see and describe single

celled organisms (protozoa)celled organisms (protozoa)

Robert Hooke Robert Hooke (1665)(1665)

Coined term “cell”Coined term “cell”

Earliest Earliest MicroscopeMicroscope??

Parts of a Compound Parts of a Compound MicroscopeMicroscope

Contain two lenses Contain two lenses that cause light rays to that cause light rays to bend in such a way to bend in such a way to produce an enlarged produce an enlarged image.image.

Lenses:Lenses:

Ocular LensOcular Lens: eyepiece lens: eyepiece lens

Objective LensObjective Lens: can be low, medium or high : can be low, medium or high powerpower

Look at magnification on lensLook at magnification on lensLower power is smaller in sizeLower power is smaller in size

Letting in Letting in Light:Light:

Mirror or IlluminatorMirror or Illuminator: : directs light up through directs light up through the specimenthe specimen

DiaphragmDiaphragm: regulates : regulates amount of lightamount of light– Disk with different sized Disk with different sized

“iris” or openings“iris” or openings

ArmArm: connects stage and : connects stage and body tubebody tube

StageStage: platform with : platform with opening over which a opening over which a specimen is placed (clips specimen is placed (clips to hold slide)to hold slide)

BaseBase: supports : supports microscopemicroscope

Eyepiece (ocular)Eyepiece (ocular): part : part you look through, holds you look through, holds ocular lens, magnifies 10xocular lens, magnifies 10x

Body tubeBody tube: connects : connects eyepiece & objective lenseseyepiece & objective lenses

NosepieceNosepiece: holds objective : holds objective lenses (can be turned)lenses (can be turned)

Objective LensObjective Lens: magnifies : magnifies image, can be low, image, can be low, medium, high powermedium, high power

Focusing:Focusing:

Coarse Adjustment Coarse Adjustment KnobKnob: :

use on low power only!!use on low power only!! (never use with high power(never use with high poweryou can break your slide!)you can break your slide!)

Fine Adjustment KnobFine Adjustment Knob: : once low power is focusedonce low power is focusedswitch to high power and switch to high power and

useusefine adjustment.fine adjustment.

MagnificationMagnification

How much can you enlarge the How much can you enlarge the imageimage??

Ex: 100x = 100 times as bigEx: 100x = 100 times as big

Finding Total Finding Total MagnificationMagnification Multiply strengths of two lenses Multiply strengths of two lenses

you are using.you are using.– Ocular lens x Objective lensOcular lens x Objective lens

Ex:Ex:

Ocular = 10x Ocular = 10x

High Power Objective= 45xHigh Power Objective= 45x

Total Magnification = (10 x 45) = Total Magnification = (10 x 45) = 450x450x

PracticePractice

Find Total MagnificationFind Total Magnification::

1.1. Ocular 2x, Objective 30x = Ocular 2x, Objective 30x =

2.2. Ocular 10x, Objective 60x = Ocular 10x, Objective 60x =

3.3. If Ocular is 10x and Total mag. = If Ocular is 10x and Total mag. = 350x350x

What is the strength of the objective What is the strength of the objective lens?lens?

Note: Note:

As you increase magnification you As you increase magnification you need to let in more light to see need to let in more light to see your specimen (adjust your specimen (adjust diaphragm)diaphragm)

ResolutionResolution

How sharp can you get the imageHow sharp can you get the image??

Ability of microscope to distinguish Ability of microscope to distinguish two objects as being separate (ex: two objects as being separate (ex: one cell from another)one cell from another)

What Happens to What Happens to Image?Image? Compound MicroscopesCompound Microscopes::

– Image becomes inverted and upside Image becomes inverted and upside downdown

What Happens to What Happens to Image?Image? When you increase magnificationWhen you increase magnification

– Object appears largerObject appears larger– Field of view gets smallerField of view gets smaller

Finding Field of View Finding Field of View (F.O.V)(F.O.V)

Under Low PowerUnder Low Power: Use millimeter : Use millimeter ruler ruler

Ex: 1.5mmEx: 1.5mmConvert to micrometersConvert to micrometers

1 mm = 1000 micrometers1 mm = 1000 micrometers

So 1.5 mm = 1,500 micrometersSo 1.5 mm = 1,500 micrometers

(Move decimal over 3 to right)(Move decimal over 3 to right)

Finding Field of View Finding Field of View (F.O.V)(F.O.V) Under Medium or High PowerUnder Medium or High Power

Need to set up a proportion Need to set up a proportion

Remember!! Remember!! – As magnification increases FOV As magnification increases FOV

decreasesdecreases

Low power MagnificationLow power Magnification = = High power High power FOVFOV

High power Magnification Low power High power Magnification Low power FOVFOV

Ex: Ex: 100x100x = = HP FOVHP FOV500x500x 1500 micrometers1500 micrometers

500x = 150000500x = 150000HP FOV = 300 micrometersHP FOV = 300 micrometers

Determining the Size Determining the Size of an Object Under a of an Object Under a MicroscopeMicroscope

View and draw object on low View and draw object on low powerpower

Estimate how many objects would Estimate how many objects would fit across diameter of field of viewfit across diameter of field of view

Divide the Divide the diameter of FOV by diameter of FOV by the number of the number of objects that can fit objects that can fit across it.across it.

Ex: Ex: – Three letter “e”s fit Three letter “e”s fit

across FOV of 1800 across FOV of 1800 micrometersmicrometers

– Each letter is about Each letter is about 600 micrometers600 micrometers

1800 micrometers = 600 µm

3 letter “e”

Comparing Comparing MicroscopesMicroscopes

Compound Light MicroscopeCompound Light MicroscopeMagnification 40x – 1500xMagnification 40x – 1500x– 2-D image, inverted, upside down2-D image, inverted, upside down– Uses stains to see details (may kill Uses stains to see details (may kill

specimen)specimen)– Specimen must be thin to allow light Specimen must be thin to allow light

throughthrough

Dissecting MicroscopeDissecting Microscope::

Low mag. 10x – 20xLow mag. 10x – 20x See See true imagetrue image (right side up) (right side up) Specimen can be aliveSpecimen can be alive Can use tools for dissecting specimenCan use tools for dissecting specimen Binocular (two ocular lens) so you can Binocular (two ocular lens) so you can

see 3-D imagesee 3-D image

Phase Contrast MicroscopePhase Contrast Microscope:: Uses special filters to show depth Uses special filters to show depth

without stainingwithout staining. . Can see interior details of Can see interior details of livingliving

cellscells

Electron Microscopes:Electron Microscopes: Much higher magnification and resolution Much higher magnification and resolution

than microscopes that use light. than microscopes that use light. Magnifies up to 200,000xMagnifies up to 200,000x Uses beam of electronsUses beam of electrons Sample placed in vacuumSample placed in vacuum Cannot view living specimensCannot view living specimens Allowed scientists to see structure of Allowed scientists to see structure of

cellular organellescellular organelles

Other EquipmentOther Equipment

CentrifugeCentrifuge::– Separates cell components by Separates cell components by

densitydensity– Whirls test tubes at high speedWhirls test tubes at high speed– Heaviest at bottomHeaviest at bottom

Micro-dissecting ToolsMicro-dissecting Tools Used to dissect cellsUsed to dissect cells