General Bio II Manual

General Bio II Manual - BIOLOGY 2.5 GENERAL BIOLOGY II...

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BIOLOGY 2.5 GENERAL BIOLOGY II LABORATORY MANUAL Fourth Edition Department of Biology Brooklyn College Fall 2010
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General Biology II Laboratory Manual 3 CONTENTS 1 Microscopy 2 Eukaryotic Cell Organization 3 Proteins I 4 Proteins II 5 Nuclear DNA 6 Spectrophotometry 7 Midterm Examination 8 Polymerase Chain Reaction (PCR) 9 Bacterial Transformation 10 Plasmids 11 Restriction Endonucleases 12 Agarose Gel Elelctrophoresis II 13 Computer Analysis of DNA Sequences 14 Examination 15 Appendix
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General Biology II Laboratory Manual 4 I hear, and I forget I see, and I remember I do, and I understand
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General Biology II Laboratory Manual 5 1 MICROSCOPY I. Principles of Microscopy One of the earliest uses of lenses to magnify objects was discovered when excavations of ancient Nineveh uncovered a plano-convex lens of rock crystal dating to 721-705 B. C. Although the 17th century scientist Anthony Van Leeuwenhoek was one of the first to engage in serious scientific inquiry using the microscope to amplify specimens invisible to the unaided eye, development of the modern compound microscope dates to at least 1590 when Zaccharias Janssen of Holland experimented with several lenses housed in a simple tube whose length could be extended to almost 6 feet. Rapid progress was made in the development of the compound microscope during the 19th century, and resolution achieved by these instruments is still a standard by which modern instruments are judged. An essential property of all microscopes is their resolving power. Resolution is the ability to distinguish between two closely positioned objects and is a more important parameter than magnification. The resolving power of a microscope is related to the wavelength of the illuminating light, the size of the cone of light entering the lens from the
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General Biology II Laboratory Manual 6 specimen, and the degree to which a medium bends a light ray that passes through it, a parameter known as refractive index. Decreasing the wavelength or increasing either the refractive index or the size of the cone of light entering the specimen will improve resolution. A. Understanding Contrast in Light Microscopy To understand contrast in light microscope images, a brief description of the properties of light waves is helpful. The wave nature of light is illustrated in Figure 1. Figure 1. The distance from one peak or valley in a wave to the next peak or valley is referred to as wavelength. The height of each peak is known as amplitude. Wavelength determines the color of the light, whereas amplitude determines its intensity. Because most cells are colorless and translucent, the contrast of a magnified image must be enhanced in order to see details of cellular structure. When light passes through an unstained cell, the amplitude of the light rays are not significantly
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General Biology II Laboratory Manual 7 changed, and structural details cannot be seen. When the image is magnified, there is no significant change in amplitude of the emerging
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General Bio II Manual - BIOLOGY 2.5 GENERAL BIOLOGY II...

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