CHAPTER 6
PROKARYOTE AND EUKARYOTE

MICROSCOPE INVENTORS
 16th century  Magnifying glass was introduced  magnification 5 x

Anton van Leeuwenhoek (1683)  Invent a primitive microscope (magnification = 266 x)  Looked at everything from rainwater to tears  saw swimming living cells (microbes) He called as “animalcules”

MICROSCOPE INVENTORS
Robert Hooke (1665)  See non-living particles  invents the term “cell” after viewing slices of cork through a very primitive microscope

MICROSCOPE INVENTORS
The discovery and early study of cells progressed with the invention and improvement of microscopes in the 17th century Light microscopy

LIGHT MICROSCOPE
 Compound or light microscope
 Visible light rays passes through specimens and uses glass lenses to view objects  Different magnification of objective lense range from 4x, 10x, 40x, and 100x  The lenses refract light such that the image is magnified into the eye

LIGHT MICROSCOPE
 Magnification
 Magnification is the ratio of an object’s image to its real size. Resolving power is a measure of image clarity.  It is the minimum distance two points can be separated and still viewed as two separate points.  Resolution is limited by the wavelength of the source, in this case light.

LIGHT MICROSCOPE
 Light microscopes can magnify effectively to about 1,000 times the size of the actual specimen  At higher magnifications, the image blurs.  Light microscope can resolve individual cells, it cannot resolve much of the internal anatomy, especially the organelles.

ELECTRON MICROSCOPE
 To resolve smaller structures we use an electron microscope (EM)  which focuses a beam of electrons through the specimen or onto its surface. Because resolution is inversely related to wavelength used, electron microscopes with shorter wavelengths than visible light have finer resolution. 