Lecture _5 - Cell Structure

Lecture _5 - Cell Structure - The The Cell Structure...

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he Cell Structure The Cell Structure Lecture #5 Campbell –Reece, 8 th Edition Reading Assignment: Chapters 6 BIOL 203 – Spring 2010 Ralph Feuer
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The Cell is the Basic Unit of Life atthias Jacob Schleiden & Theodor Schwann Matthias Jacob Schleiden & Theodor Schwann proposed the Cell Theory in 1839 Colored Fibers - Cytoskeleton “life is composed of cells, cells arise only from pre-existing cells, and the cell is the fundamental unit of structure and function in living organisms” Some organisms are unicellular (e.g. bacteria, amoeba, yeast) Some organisms are multicellular (e.g. humans, plants)
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10 m Human height How Do We Look At Cells? 1 m Length of some nerve and muscle cells Chicken egg 0.1 m Unaided eye 1 cm Frog egg 1 mm Usually with some sort of microscope. Light Microscope can be used to look at structures as small as 1/4 micron because 100 μm Most plant and animal cells 10 μm Nucleus ght microscope m/ m the wavelength of light is about 1/2 micron. Can look at live cells. 1 μm Most bacteria Mitochondrion Smallest bacteria 00 nm Li g microscope Electron Microscope is needed to look at smaller structures. Cannot look at live cells. Viruses 100 nm 10 nm Ribosomes Proteins Lipids Electron X-ray X-ray Diffraction or nmr spectroscopy normally used to determine atomic resolution structures 1 nm Small molecules Atoms 0.1 nm Measurements 1 centimeter (cm) = 10 –2 meter (m) = 0.4 inch 1 millimeter (mm) = 10 –3 m 1 micrometer (μm) = 10 –3 mm = 10 –6 m 1 nanometer (nm) = 10 –3 μm = 10 –9 m nm r
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TECHNIQUE RESULTS (a) Brightfield (unstained specimen) Light Microscopy (LM) (b) Brightfield (stained specimen) 50 μm (c) Phase-contrast LM Can magnify effectively to about 1,000 times the size of e actual specimen (d) Differential-interference- contrast (Nomarski) the actual specimen Various techniques nhance contrast and enable (e) Fluorescence Enhance contrast and enable cell components to be stained or labeled (f) Confocal 50 μm Most subcellular structures Too small to be resolved by an LM Organelles 50 μm Membrane-enclosed compartments
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Electron Microscopy (EM) TECHNIQUE RESULTS Two basic types of (a) Scanning electron microscopy (SEM) Cilia 1 μm electron microscopes (EMs) used to study subcellular structures Scanning electron microscopes (SEMs) Focus a beam of electrons onto the rface of a specimen (b) Transmission electron microscopy (TEM) Longitudinal section of cilium Cross section of cilium 1 μm surface of a specimen Providing images that look 3-D Transmission electron icroscopes (TEMs) microscopes (TEMs) Focus a beam of electrons through a specimen Used mainly to study the internal structure of cells
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Two Types of Cells Bacteria (eubacteria) and Animals and Prokaryote Archaea (archaebacterium) Plants Eukaryote Cell bounded by Plasma Membrane Cell bounded by Plasma Membrane Contains semifluid cytosol Contains semifluid cytosol ontains NA ontains NA Contains DNA Contains DNA Contains Ribosomes (make proteins) Contains Ribosomes (make proteins) o Nucleus ucleus: ontains DNA No Nucleus Nucleus: contains DNA
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This note was uploaded on 03/07/2010 for the course BIO 203 taught by Professor Feuer during the Spring '10 term at San Diego State.

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Lecture _5 - Cell Structure - The The Cell Structure...

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