Section 3-1

Heather Sullivan- FRHSDHeather Sullivan- FRHSD

Describe how scientists measure the length of objects.

Relate Magnification & Resolution in the use of microscopes

Analyze how a light microscope functions

Compare a Light Microscope with an Electron Microscope

Measuring Cell Structures Scientists use the metric system to measure

the sizes of objects viewed under a microscope.

Characteristics of Microscopes enable biologists to examine the details of cell

structure and to understand how organisms function. Magnification and resolution are two quantitative characteristics of microscopes.

Compound Light Microscope Light microscopes have a low magnification and

can be used to examine living cells.

Electron Microscopes Electron microscopes have a high magnification

but cannot be used to examine living cells.

Scanning Tunneling Microscope The scanning tunneling microscope uses a

computer to generate a three-dimensional image of the object.

Magnification Low Power (LP)= 40x MP=100x HP=400x

Micrograph Image seen

FOV Field of view

Benefits Specimen can still be alive Fairly inexpensive

Pine Pollen 2000x

Shoots a beam of electrons through a specimen to illuminate it

Must be in a vacuum so electrons don’t bounce off air molecules

Can’t study living cells

Benefits Can study cell details &

cell surface Creates 3-D image

Hibiscus Pollen 200,000x