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MICROSCOPES

MICROSCOPES. Naomi Kinjal Asaad Binoy. Microscopy. Magnification is the ratio of an object’s image size to the real size Resolution is a measure of the clarity of the image; it is the minimum distance two points can be separated and still distinguished as two points.

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MICROSCOPES

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  1. MICROSCOPES Naomi Kinjal Asaad Binoy

  2. Microscopy • Magnification is the ratio of an object’s image size to the real size • Resolution is a measure of the clarity of the image; it is the minimum distance two points can be separated and still distinguished as two points

  3. Different Types of Microscopes • Light-visible- light is passed through the specimen and then through a glass lens. Specimen can be living or not; stained. Resolving power is limited by the wavelength of visible light. • Electron-focuses a beam of electrons through the specimen or onto it’s surface; helps see cell organelles but not living specimen. Resolving power is larger since wavelengths of electrons are smaller than light

  4. Electron Microscopy Techniques • Scanning electron microscopy (SEM)-micrographs taken with a scanning electron microscope show a 3-D image of the surface of a specimen. useful for the detailed study of the surface of the specimen • Transmission electron microscopy (TEM)-a transmission electron microscope profiles a thin section of a specimen. used to study the internal ultrastructure of cells

  5. Light Microscopy Techniques • Brightfield (unstained specimen)-passes light directly through specimen • Brightfield (stained specimen)-staining with various dyes enhances contrast • Phase-contrast-enhances contrast in unstained cells by amplifying variations in density within specimens • Differential-interference-contrast (Nomarski)-uses optical modifications to exaggerate differences in density • Fluorescence-shows the locations of specific molecules in the cell by tagging the molecules with fluorescent dyes or antibodies • Confocal-a technique that uses a pinhole aperture to eliminate out-of-focus light from a thick sample

  6. Uses for Microscopes • Tissue Analysis-common for studying cells and tissues • Studying the Role of a Protein within a Cell-helps study proteins in live cells • Studying Atomic Structures-helps study the surfaces of individual atoms

  7. Facts • Cell walls were first seen by Robert Hooke in 1665 as he looked through a light microscope at dead cells from the bark of an oak tree • It took Antoni van Leeuwenhoek's crafted lenses to help visualize living cells • Cell biology advanced rapidly in the 1950s with the introduction of electron microscope • Most cells are between 1 and 100 micrometers in diameter and are therefore visible only under a microscope • Microscopes are the most important tools of cytology, the study of cell structure • Modern cell biology developed from an integration of cytology with biochemistry

  8. Limitations • Size of specimen • Encounter diffraction • Many cells are transparent and colorless- staining can kill specimen

  9. http://www.youtube.com/watch?v=Swcz_TJMz0I • http://www.youtube.com/watch?v=U2Uy2BXgUio

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