EXAM 2 REVIEW - EXAM 2 REVIEW 1 cell theory all organisms...

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EXAM 2 REVIEW 1. cell theory all organisms consist of cells, and all cells come from preexisting cells. 1) cells are fundamental units of life. 2) all organisms are composed of cells. 3) all cells come from preexisting cells. 2. Leeuwenhoek father of microbiology. Improved microscope and microbiology. First to observe and describe microorganisms. Hook Virchow “every cell originates from another cell,” leukemia, embolism. Schlieden Schwann Pasteur 3. Distinguish between prokaryotic and eukaryotic cells. Prokaryotic Eukaryotic Nucleoid contains DNA Nucleus contains DNA Bacteria and Archaea Protists, plants, fungi, animals Smaller 1-10 microns Larger 10-100 microns Mesosomes, but few organelles Many membrane-enclosed organelles Long evolutionary history Recent evolution Circular chromosome Double helix in rod-like form 4. What is the average size of a prokaryotic cell? Between 1-10 microns. A eukaryotic cell? Between 10-100 microns. 5. Describe the techniques used in light microscopy to enhance the image. - Bright-field microscopy – light passes through cells. Little contrast and details - Phase-contrast – contrast increased by stressing differences in refractive index - Differential interference-contrast – 2 beams of polarized light (shadow) - Fluorescence – substance or dye that binds to cell material is stimulated by beam - Confocal – fluorescent; stimulating and emitted light so single plane is seen - Stained bright-field – stain added enhances contrast and reveals details - TEM – beam of electrons focused on object by magnets; dark if electrons absorbed. - SEM – directs electrons to surface, causing other electrons to be emitted. 3D - Cryoelectron – quickly frozen samples to reduce abnormality. 3D 6. What is the smallest size that can be resolved using your eye? 0.2 mm. A light microscope? 1,000 x human eye, 0.2 micrometers. An electron microscope? 0.5 nm, 400,000 x human eye. 7. How many microns in a millimeter? 1,000,000. How many nanometers in a micron? 1,000. 8. What is the difference between SEM and TEM? SEM emits electrons on the surface. 9. How are fluorescent antibodies used in microscopy? Antibodies combine with fluorochrome binds to the cell to produce an image. 10. Explain how the surface-to-volume ratio of a cell is related to its ability to take in resources and to rid itself of wastes. Surface area determines amount of substances the cell can take in from the outside environment and amount of wastes it can release to the
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environment. As cells grow, its rate of waste production and need for resources increase
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