Chapter 7: Section 7.1 MICROSCOPES

MOST IMPORTANT TOOL OF THE LABORATORY FOR STUDYING MICROORGANISMS

TERMS• Magnification –      • Resolution –      • Contrast —      

PRINCIPLES OF LIGHT MICROSCOPY• Magnification

Microscope has       magnifying lensesCalled compound microscope

• Lens includeOcular lens (eyepiece) and objective lensLenses combine to       objects

• Magnification is equal to: multiplying the ocular lens (     ) x the      ex: 10x X 100x = 1,000x

EFFECT OF MAGNIFICATIONPRINCIPLES OF LIGHT MICROSCOPY

• Resolution• Resolving power determines how much       can be seen» Resolution is enhanced with lenses of higher magnification (100x)

TYPES OF MICROSCOPES

COMPOUND LIGHT MICROSCOPE• Light Microscopy

Light passes through specimen, then through series of magnifying lensesMost common and easiest to use is the       microscope

ELECTRON MICROSCOPE• Electron Microscopy– Uses       lenses,       and fluorescent screen to produce image– Resolution increased 1,000 fold over compound light microscope– Magnification increased to      

– Two types of electron microscopes1.      2.      

1. Transmission Electron Microscope (TEM)-     - Directs beam of electrons at specimen- Electrons pass through or scatter at surface-     - Darker areas more dense

2. Scanning Electron Microscope (SEM)- Used to observe      - Beam of electrons scan surface of specimen- Specimen coated with metal. Usually      - Electrons are released and reflected into viewing chamber

- Some atomic microscopes capable of seeing single atoms