113lecture0406 - BIOLOGY 113 MICROBIOLOGY Lecture 4...

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BIOLOGY 113 - MICROBIOLOGY Lecture 4: Prokaryotic Cell Biology - Structures external to the cell membrane The cells of bacteria can be distinguished from those of all other forms of cellular life (fungi, protozoans, plants and animals) by their prokaryotic organization - In contrast to the situation with eukaryotic cells, the DNA of prokaryotic cells is not enclosed in a separate nuclear compartment = Also, the DNA of eucaryotic cells is always associated with specific chromosomal proteins, the histone. Histone-like proteins are found in some prokaryotic cells, but are not common = The DNA of prokaryotic cells does not become condensed into the "chromosomes" with which we're familiar in eucaryotic cells; nevertheless, we refer to the DNA molecules of prokaryotic cells as chromosomes. - Prokaryotic cells also lack other membrane-bound organelles - mitochondria, endoplasmic reticulum, chloroplasts - found in eucaryotic cells - It's important to note that, with all of these differences, prokaryotic cells carry out all of the functions of cells; for example, while they lack mitochondria for respiration, they may carry respiratory enzymes in the cytoplasmic membrane - Although prokaryotic bacterial cells may seem relatively "simple" when compared to those of eucaryotes, they do exhibit considerable structural complexity (Tortora et al., Figure 4.5) Bacterial cells are usually very small, less than 2 μm (2 1/1000ths of a millimeter) in diameter. - The shape ( cocci, bacilli, or spirilla) and arrangement of bacterial cells can be very useful for identification in the laboratory (Tortora et al., Figures 4.1, 4.2 and 4.3) - It's important to note that environmental conditions can influence the shape and arrangement of bacterial cells The cytoplasmic membrane of a typical prokaryotic cell is surrounded by a cell wall; a variety of
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This note was uploaded on 11/24/2011 for the course BIO 113 taught by Professor Staff during the Fall '09 term at Rutgers.

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113lecture0406 - BIOLOGY 113 MICROBIOLOGY Lecture 4...

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