chapter_2_outline_spr09

chapter_2_outline_spr09 - 01/15/09 Chapter 2: Observing the...

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01/15/09 Chapter 2: Observing the Microbial Cell SIZE OF PROKARYOTES Prokaryotes are generally smaller than eukaryotes Small size allows nutrients to reach all parts of cell quickly and waste products are able  to leave quickly Prokaryotic cells can be as small as 0.2μm.  The smallest eukaryotic cells are 2μm.  Cocci-typically has diameter of 2 µm Some microbiologists have proposed that bacteria smaller than 0.2 μm exist in nature,  cells referred to as nanobacteria and haven’t been discovered yet.  If one considers the space needed to house all essential molecules of life, it is unlikely  they could exist within a volume available in a cell less than 0.1 μm. Prokaryotic cells can have a wide variety of cellular morphologies, which are often  helpful in identification. Bacterial Shapes 1. Simplest shape is sphere o singular-coccus  o plural- more than one sphere- cocci Arrangement: o Coccus- a single cell o Diplococcus-  2 cells stuck together o Streptococcus- chains of  more than 2 cells o Staphylococcus-grapelike cluster of cells; ex:  Staphylococcus aureus  is an  organism which grows as staphylococci o Tetrads- packets of 4 cells 2. Most common shape is rods o Singular- bacillus o Plural-  more than one rod- bacilli Occur singly or in chains Never see staphylobacillus- clusters of bacilli 3. Spirals: Rigid spiral-shaped bacteria are called spirilla (singular-spirillum) Flexible spiral-shaped bacteria are called spirochetes- flexible corkscrew shape Vibrio – curved rods Microscopy
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Simple microscopes o one lens o magnify 50 – 300 X Compound microscopes o multiple lenses o Much higher  magnification The ones in 2051 lab magnify 1000x  Lens System of Compound Microscopes Condenser lens o  located between light source(light bulb) and  specimen (slide) o Focuses light rays up through specimen Objective lens system o Closest to specimen
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This note was uploaded on 03/08/2009 for the course BIOL 2051 taught by Professor Brininstool during the Spring '07 term at LSU.

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chapter_2_outline_spr09 - 01/15/09 Chapter 2: Observing the...

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