Outline Chapter 6

Outline Chapter 6 - Chapter 6 A Tour of the Cell I The...

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Chapter 6: A Tour of the Cell I. The Fundamental Units of Life a. Cells = simplest forms of matter that can live II. To study cells, biologists use microscopes and the tools of biochemistry a. Microscopy i. Light microscope – visible light is passed through the specimen and then through glass lenses – lens refract light so that image is magnified as it is projected into the eye, onto photographic film or digital sensor, onto a video screen ii. Magnification – ratio of object’s image size to its real size. Resolution is measure of the clarity of the image. Minimum distance two points can be separated and still be distinguished as two points. iii. Resolve – contrast – accentuates different in light iv. Organelles too small to be seen by light microscope. Use electron microscope = beam of electrons onto specimen. Resolution inversely related to wavelength of radiation microscope uses for imaging and electron beams have shorter wavelengths than invisible light. v. Scanning electron microscope – electron beam scans surface. Electrons detected by device that translates pattern into signal. Good DOF vi. Transmission electron microscope – study internal ultrastructure of cells. Electron beam through very thin section of the specimen, similar to the way a light microscope transmits light through a slide. Specimen stained with atoms of heavy metals, which attach to certain structures = enhance electron density of parts of cells more than others. The electrons passing through denser regions are scattered more. Tem use electromagnets as lenses to bend paths of electrons = focus image onto screen for viewing onto photographic film. vii. Show many organelles, but also kills cells. viii. Cytology – study of cell structure. ix. Biochem – study of molecules and chemical processes of cells b. Cell Fractionation i. Cell fractionation – cells apart and separates major organelles and other subcellular structures from one another = centrifuge ii. Fraction of cell components settle at the bottom and higher speed means pellet with smaller components iii. Allows researchers to prepare specific cell components in bulk and identify their functions. III. Eukyarotic cells have internal membranes that compartmerRNA is synthesized. Nucleus directs synthesis byntalize their functions a. Comparing Prokaryotic and Eukaryotic cCells i. Plasma membrane common ii. Cytosol – jellylike substance
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iii. Chromosomes carry genes in form of DNA iv. Eukaryotic cell – DNA is in nucleus bound by double membrane v. Prokaryotic cell – DNA in region called nucleoid. Interiorof cell is called cytoplasm – area between nucleus and plasma membrane of eukaryotic cell. vi. Eukaryotic cells are generally larger. vii.
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Outline Chapter 6 - Chapter 6 A Tour of the Cell I The...

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