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Unformatted text preview: Chapter 4 Prokaryotic Cell Structure and Function Introduction 4.1 Prokaryotic Diversity The Domain Bacteria Contains Some of the Best Studied Prokaryotes The majority of the 18 phyla of Bacteria play a positive role in nature Proteobacteria contain the largest and most diverse group of species, including E. coli and many human pathogens Firmucutes consist of many gram-positive species, such as Bacillus , Clostridium , Staphylococcus , and Streptococcus Actinobacteria include Streptomyces , the genus that produces the antibiotic streptomycin Cyanobacteria carry out photosynthesis using chlorophyll, responsible for the appearance of oxygen in Earths early atmosphere Chlamydiae are extremely small, mostly pathogenic bacteria The Domain Archaea Contains Many Extremophiles Euryarchaeota contain methanogens (live in anoxic environments), extreme halophiles (salt- lovers), and thermoacidophiles (grow at high temperatures with low pH) Crenarchaeota tend to grow in hot, acidic environments such as hot springs and volcanic vents 4.2 The Shapes and Arrangements of Parokaryotic Cells Prokaryotes Vary in Cell Shape and Cell Arrangement A bacillus is a prokaryotic cell with a rod shape A spherical bacterial cell is a coccus Many cocci and some bacilli appear in groups or chains Spiral shaped bacteria can appear as vibrios (comma-shaped), spirilla (helical), or spirochete 4.3 An Overview to Prokaryotic Cell Structure Structure and organization are based on specific processes cells need to carry out: sensing/responding to stimuli, compartmentation of metabolism, and growth and reproduction...
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- Spring '08