THE MICROSCOPETHE MICROSCOPE

Invention of the MicroscopeInvention of the Microscope

• The microscope was invented by a trio of Dutch eyeglass makers in the late 1500s and magnified objects up to 9x

• The invention of the microscope allowed scientists to view cells for the first time.

• In 1665, Robert Hooke published his drawings of cells, but these were the cell walls of cork cells; the cells were no longer living

• In the early 1670s, Anton van Leeuwenhoek was the first person to examine living cells

Types of MicroscopesTypes of Microscopes

• There are two types of microscopes:– Light microscopes– Electron

microscopes

Light MicroscopeLight Microscope

• Uses either sunlight or artificial light to view objects.

• The object being viewed must be thin enough for light to pass through.

• The advantage of a light microscope is that it can magnify many microscopic organisms while they are still alive.

• The disadvantage of this microscope is that it can only magnify about 1000x.

Electron MicroscopeElectron Microscope

• These microscopes either:– pass electrons through a thin slice of an

object (transmission electron microscope or TEM)

– examine the outside of an object (scanning electron microscope or SEM)

• The advantage of this microscope is that they can magnify objects up to one million times their actual size.

Electron Microscope (cont.)Electron Microscope (cont.)

• The biggest disadvantage of this microscope is that specimens must be fixed in position and placed in a vacuum so organisms can not be alive.

MagnificationMagnification

• Magnification makes the image look larger.

• To find the magnification, multiply the magnification of the ocular lens by the magnification of the objective lens.

• EX: 4x objective and a 10x ocular lens will give a magnification of 40x.

ResolutionResolution

• Resolution is the ability to distinguish between two points.

• The better the resolution, the sharper the image.

• Look at the images on the next page. Even though we increased the magnification, the second image is blurry because of poor resolution.

Magnification and ResolutionMagnification and Resolution

Dyes/StainsDyes/Stains

• Used to color a specimen and thus improve the contrast between different parts of a specimen.

• Staining, however, usually kills the specimen.