Chapter 2

Chapter 2 - Chapter2 SIZEOFPROKARYOTES .2m. cellsare2m...

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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 Prokaryotic cells can be as small as 0.2μm.  The smallest eukaryotic  cells are 2μm.  Cocci (spherical)- typically have diameter of 2 µm Some microbiologists have proposed that bacteria smaller than 0.2 μm  exist in nature, cells referred to as nanobacteria 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  (shape), which are often helpful in identification. Bacterial Shapes 1. Simplest shape is sphere o singular - coccus o plural - cocci Arrangement: o Coccus- single cells o Diplococcus- 2 cells o Streptococcus- chains of  more than 2 cells 
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o Staphylococcus- grapelike cluster of cells o Tetrads- packets of 4 cells 2. Most common shape is rods o Singular- bacillus o Plural- bacilli Occur singly or in chains 3. Spirals: Rigid spiral-shaped bacteria are called spirilla (singular - spirillum) Flexible spiral-shaped bacteria are called spirochetes Vibrio – curved rods Microscopy Simple microscopes o one lens o magnify 50 – 300X Compound microscopes o multiple lenses o Much higher magnification Ones in 2051 lab magnify 1000x
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Lens System of Compound Microscopes Condenser lens o located between light source and specimen
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This note was uploaded on 06/15/2011 for the course BIOL 2051 taught by Professor Brininstool during the Summer '07 term at LSU.

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Chapter 2 - Chapter2 SIZEOFPROKARYOTES .2m. cellsare2m...

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