Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.1Chapter 3Procaryotic Cell Structure and FunctionCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.2An Overview of Procaryotic Cell Structure• a wide variety of sizes, shapes, and cellular aggregation patterns• simpler than eucaryotic cell structure• unique structures not observed in eucaryotesCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.3Size, Shape, and Arrangement• cocci (s., coccus) – spheres– diplococci (s., diplococcus) – pairs– streptococci – chains– staphylococci – grape-like clusters– tetrads – 4 cocci in a square– sarcinae – cubic configuration of 8 cocciCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.4Size, Shape, and Arrangement• bacilli (s., bacillus) – rods– coccobacilli – very short rods– vibrios – curved rods• mycelium – network of long, multinucleate filamentsCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.5Size, Shape, and Arrangement• spirilla (s., spirillum) – rigid helices• spirochetes – flexible helices• pleomorphic – organisms that are variable in shapeCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.6•largest –≥50 µm indiameter• smallest –0.3 µm in diameterFigure 3.3Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.7Procaryotic Cell OrganizationCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.8Figure 3.4Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.9Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.10Procaryotic Cell Membranes• membranes are an absolute requirement for all living organisms• plasma membrane encompasses the cytoplasm• some procaryotes also have internal membrane systemsCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.11The Plasma Membrane• contains lipids and proteins– lipids usually form a bilayer– proteins are embedded in or associated with lipids• highly organized, asymmetric, flexible, and dynamicCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.12The asymmetry of most membrane lipids• polar ends– interact with water– hydrophilic• nonpolar ends– insoluble in water– hydrophobicFigure 3.5Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.13Other membrane lipidsFigure 3.6Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.14Membrane proteins• peripheral proteins– loosely associated with the membrane and easily removed• integral proteins– embedded within the membrane and not easily removedCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.15Figure 3.7Fluid mosaic model of membrane structureCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.16Archaeal membranes• composed of unique lipids• some have a monolayer structure instead of a bilayer structureCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.17Functions of the plasma membrane• separation of cell from its environment• selectively permeable barrier– some molecules are allowed to pass into or out of the cell– transport systems aid in movement of moleculesCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.18More functions…• location of crucial metabolic processes• detection of and response to chemicals in surroundings with the aid of special receptor molecules in the membraneCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.19Internal Membrane Systems• mesosomes– may be invaginations of the plasma membrane• possible roles– cell wall formation during cell division– chromosome replication and distribution– secretory processes– may be artifacts of chemical fixation processCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.20Other internal membrane systems• complex in-foldings of the plasma membrane– observed in many photosynthetic bacteria and in procaryotes with high respiratory activity– may be aggregates of spherical vesicles, flattened vesicles, or tubular membranesCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.21The Cytoplasmic Matrix• substance between membrane and nucleoid• packed with ribosomes and inclusion bodies• highly organized with respect to protein locationCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.22Figure 3.10Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.23Inclusion Bodies• granules of organic or inorganic material that are stockpiled by the cell for future use• some are enclosed by a single-layered membrane– membranes vary in composition– some made of proteins; others contain lipidsCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.24Organic inclusion bodies• glycogen– polymer of glucose units• poly-β-hydroxybutyrate (PHB)– polymers of β-hydroxybutyrateCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.25Organic inclusion bodies• cyanophycin granules– large polypeptides containing about equal quantities of arginine and aspartic acid• carboxysomes– contain the enzyme ribulose-1,5,-bisphosphate carboxylaseCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.26Organic inclusion bodies• gas vacuoles– found in cyanobacteria and some other aquatic procaryotes– provide buoyancy– aggregates of hollow cylindrical structures called gas vesiclesCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.27Figure 3.12aCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.28Figure 3.12bCopyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or