TestReview-Test2Outlines

TestReview-Test2Outlines - Chapter 6- A tour of the Cell...

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Chapter 6 - A tour of the Cell Microscopy - began in the 1590s and improved through the 17 th century. o Light Microscopes - visible light is passed through the specimen and then through lenses that bend the light and magnify the object to allow viewing by the viewer. o Magnification is the ratio of the object’s actual size to its size while viewing. o Resolving power refers to the ability to discriminate between objects in the specimen while viewing it in the microscope. The finest detail that a light microscope can distinguish is 200 nm. It is limited by the shortest wavelength of light used to illuminate the specimen. o Electron microscopes use a beam of electrons aimed through a specimen or onto its surface. Magnets provide the same function that lenses do in light microscopes. SEM reveals the surface characteristics of a specimen by passing electrons onto the surface of a specimen that is usually covered in a thin film of gold. The beam excites electrons on the surface of the specimen (the gold), and these secondary electrons are captured by a device that sends the information to a screen, and a topography of the specimen is produced. TEM reveals the ultra-structure of the cell. It passes a beam of electrons through a thin slice of the specimen. The specimen has been treated with heavy metals that bind to specific structures in the cell. The electrons are then deflected by these metals, and magnets are used to “focus” the image that is produced onto a film, camera, or screen. Cell fractionation is to take cells apart to identify and study structures within the cell. o The centrifuge is used for this purpose. It spins samples at varying multiples of the force of gravity. By using this, scientists are able to attain bulk quantities of the structure that they wish to study.
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Eukaryotic Cells Both Prokaryotic Cells Nucleus Organelles larger Plasma membrane Cytosol Chromoso mes Ribosomes Nucleoid smaller Nucleus - center of genetic material o Separated by the nuclear envelope Double membrane Perforated with pores Supported by the nuclear lamina o Chromosomes make up genetic material. Each one is made of chromatin . o Nucleolus is located in the center of the nucleus. It is here that rRNA is assembled No membrane
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Ribosomes are protein factories of the cell. o Made of rRNA and proteins o No membrane o Free ribosomes assemble proteins in the cytoplasm. Most proteins made here are used within the Cytosol. o Bound ribosomes are attached to the RER. Proteins made here are either used in vesicles within the cell, or secreted from the cell. Cells that specialize in secretion proteins have a plethora of bound ribosomes. Endomembrane System
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TestReview-Test2Outlines - Chapter 6- A tour of the Cell...

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