ch6 - Biology Vocabulary: Chapter 6, basically an outline....

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Biology Vocabulary: Chapter 6, basically an outline. 1. Light microscopes: a microscope that passes visible light through a specimen, and then through glass lenses; the lenses refract (bend) light in such a way that the image of the specimen is magnified as it is projected into the eye 2. Organelles: sub cellular structures; cell biology advanced rapidly in 1950s with the introduction of the electron microscope 3. Electron microscope: a microscope that focuses a beam of electrons through the specimen or onto its surface a. Scanning electron microscope: especially useful for detailed study of the surface of a specimen; the electron beam scans the surface of the sample, which is usually coated with a thin film of gold; the beam excites electrons on the sample’s surface, and these secondary electrons are detected by a device that translates the pattern of electrons into an electronic signal on a video screen b. Transmission electron microscope: aims an electron beam through a very thin section of the specimen, similar to the way a light microscope transmits light through a slide. The specimen is stained with heavy metals, which attach to certain cellular structures; the image is created by the pattern of scattered electrons 4. Cell fractionation: the goal is to take cells apart and separate the major organelles from one another; enables the researcher to prepare specific components of cells in bulk quantity to study their composition and functions a. Ultracentrifuge: the instrument used to fractionate cells at various speeds; can spin as fast as 130,000 revolutions per minute 5. Cytosol: a semi fluid substance within the membrane 6. Prokaryotic cell: pro meaning “before” and karyon meaning “kernel”; cells that have no membrane-bound nucleus a. Nucleoid: place in the prokaryotic cell where the DNA is concentrated, separates from the rest of the cells 7. Eukaryotic cell: eu meaning “true” and karyon meaning “kernel”; a cell with a
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ch6 - Biology Vocabulary: Chapter 6, basically an outline....

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