Main Groups of Microorganisms Prokaryotes Bacteria and Archaea Protozoa Fungi Viruses General Characteristics of Microorganisms Most are single celled organisms Two basic cell types Prokaryotic Eukaryotic Small Size Two Basic Cell Types Prokaryotic vs Eukaryotic Cells Prokaryote Morphology and Structure Two Groups Bacteria and Archaea Use bacteria as our representative group Less complex compared to eukaryotic cells Size Thiomargarita Shapes simple morphology Not a lot of variation described by one of three basic shapes coccus spherical bacillus rod coccobacillus very short and plump vibrio gently curved spirillum helical comma twisted rod spirochete spring like Arrangements cocci singles diplococci in pairs tetrads groups of four irregular clusters chains cubical packets bacilli chains palisades Appendages Cell envelope covering Cytoplasm internal structures Appendages Flagella Fimbriae and Pili Monotrichous Lophotrichous Peritrichous Arrangement of cells is dependent on pattern of division and how cells remain attached after division Major Components of a Typical Bacterium Axial filament endoflagellum Glycocalyx S Layer Cell Wall Cell Membrane Varied chemical composition polysaccharides Proteins Function Attachment to surfaces Protection from phagocytic cells Prevent desiccation Other Fimbria Cell Envelope Glycocalyx S Layer Cell Wall Found in some types of bacteria common in Archaea Composed of protein some glycoprotein Forms very regular pattern often crystalline structure Surface of cell wall Rigid support adhesion protection Semi rigid layer Function Shape and support Protect from osmotic lysis Two main types of cell wall Gram positive Gram negative Cell Wall Osmotic Protection Terminology Gram bacteria protoplasts Gram bacteria spheroplasts Structural Components Peptidogylcan murein Main chemical providing strength Composition Polysaccharide chains linked together with peptides Two monosaccharides N acetylglucosamine NAG N acetylmuramic acid NAM Peptides Similar in structure and function to eukaryotic cell membranes Phospholipid bilayer with embedded proteins Functions in providing site for energy reactions nutrient processing and synthesis transport into and out of the cell Gel sol material Suspends solid structures Contains dissolved substances Some D configuration amino acids L is found in most protiens Some unique amino acids DAP diaminopimelic acid Gram Comparison Gram Comparison Gram Cell Wall Gram Cell Wall LPS endotoxin Cell Membrane Internal Structures Cytoplasm Chromosome Plasmid Ribosomes Inclusions Internal Membranes Endospores Nucleoid and Chromosome Nucleoid Chromosome Main piece of DNA Single circular E coli 4 639 221 bp 4 000 genes Plasmids Area in cell where chromosome is located Small circular pieces of DNA Independent from chromosome 1 20th size of chromosome May contain important genes Antibiotic resistance Toxin production Pilus formation Used in genetic engineering biotechnology Ribosome Inclusions Smaller than eukaryotic ribosomes Two pieces called subunits Medically important Site of action of many antibiotics Accumulations of certain chemicals Inorganic or organic Energy rich compounds or substance needed for certain types of metabolism Internal Membranes Plasma membrane infoldings Bacteria with membrane dependent metabolic pathways Photosynthetic bacteria Nitrifying bacteria Endospores Internal structure Formed during adverse growth conditions Contains own DNA ribosomes membrane and tough external coating Produced primarily by some Gram Bacillus Clostridium Resistant to many chemical and physical forces Disinfectants and other chemicals Radiation Heat Cold Desiccation Mechanism of resistance Precise mechanism unknown Chemical resistance due to spore coat Core contains Calcium and dipicolinic acid Small acid soluble DNA binding proteins Archaea Major differences from Bacteria Cell Wall pseudomurein or S layer only Cell Membrane no phospholipids Isoprenoid lipids ether linked to glycerol Some types with lipid monolayer End Go to Eukaryotic Morphology and Structure
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