THE MICROSCOPE Invention of the Microscope The microscope

Invention of the Microscope • The microscope was invented by a trio of Dutch

Types of Microscopes • There are two types of microscopes: – Light microscopes –

Light Microscope • Uses either sunlight or artificial light to view objects. • The

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

Electron Microscope (cont. ) • The biggest disadvantage of this microscope is that specimens

Magnification • Magnification makes the image look larger. • To find the magnification, multiply

Resolution • Resolution is the ability to distinguish between two points. • The better

Dyes/Stains • Used to color a specimen and thus improve the contrast between different

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THE MICROSCOPE

Invention of the Microscope • The microscope was invented by a trio of Dutch eyeglass makers in the late 1500 s and magnified objects up to 9 x • 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 1670 s, Anton van Leeuwenhoek was the first person to examine living cells

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

Light 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 1000 x.

Electron 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. ) • 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.

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

Resolution • 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 Resolution

Dyes/Stains • Used to color a specimen and thus improve the contrast between different parts of a specimen. • Staining, however, usually kills the specimen.