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MICROBIOLOGY Cell Biology of Bacteria Northland Community & Technical College Instructor Terry Wiseth
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2 BACTERIAL FACTS ª Scientists have named and described more than 4,000 species of bacteria ª New ones are discovered so rapidly, however, they estimate the number of unknown species in the millions ª Almost every time scientists search among bacteria in a soil or water sample, they discover previously unknown species
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3 ª The overwhelming majority of bacteria are harmless to humans or animals ª Bacteria get virus infections ª Antibiotics and other bacteria-derived materials are the basis of a $50 billion annual market for biotechnology products ª Oil spills are cleaned primarily by bacteria that feed on oil BACTERIAL FACTS
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4 ª About 10 percent of human body weight and 50 percent of the content of the human colon is made up of bacteria (Escherichia coli) ª each square centimeter of human skin hosts an average of 100,000 bacteria ª Washing removes many, but they reproduce so quickly--doubling every 20 minutes--that the population is restored in hours BACTERIAL FACTS
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5 ª So many bacteria live underground that their total weight has been estimated at 100 trillion tons ª If these microbes were spread over Earth's land surface, they would make a layer five feet thick BACTERIAL FACTS
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6 CLASSIFICATION ª Microbes « organisms smaller than the eye can detect © bacteria © fungi © protists © virus
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7 CELL TYPES ª Prokaryotes ª Eukaryotes ª Viruses
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8 PROKARYOTES ª Monera « bacteria « 1 micron diameter
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9 EUKARYOTES ª algae, protozoa and fungi ª 5 - 100 microns
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10 VIRUSES ª neither prokaryotes nor eukaryotes ª informational parasites ª each kingdom has its own associated viruses
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11 MICROBIAL SIZE Virus 0.05 to 0.1 microns Bacteria 0.5 to 1.5 microns Red blood cell 5 microns Sperm 60 microns
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12 MICROBIOLOGY ª disease ª agriculture ª food and drink ª chemical products ª basic research ª biotechnology
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PROKARYOTES VS EUKARYOTES
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14 CELL CHARACTERISTICS
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15 CELL CHARACTERISTICS
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16 CELL CHARACTERISTICS
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17 CELL CHARACTERISTICS
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18 CELL CHARACTERISTICS
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19 CELL CHARACTERISTICS
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20 CELL CHARACTERISTICS
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21 CELL CHARACTERISTICS
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BACTERIAL SHAPE
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23 BACTERIA SHAPE ª range in size from 0.20 to 2.0 micrometers in diameter « 1) Bacillus « 2) Spiral « 3) Cocci
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24 BACILLUS ª 1) Bacillus « Rod shape © Diplobacilli ¨ Two bacilli together © Streptobacilli ¨ Chains of bacilli © Vibrios ¨ curved rods
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25 BACILLUS ª Escherichia coli
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26 SPIRAL ª 2) Spiral « spirillia rigid © Spiral, helical, corkscrew shape that is rigid « spirochete flexible ª the organism is flexible and undulating
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27 COCCI ª 3) Cocci « spherical shaped © diplococci ¨ remain in pairs © streptococci ¨ chains © staphylococci ¨ clusters
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28 COCCI ª Moraxella catarrhallis ª inhabitant of the upper respiratory tract, especially the nasal cavity « notice some are in the diploid state
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BACTERIAL CELL WALL
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30 CELL MEMBRANE ª phospholipid bilayer « integral and peripheral proteins embedded « maintains the selective permeability of the cell « has respiratory enzymes
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31 CELL WALL ª cell wall surrounds the cell membrane ª Structurally, the wall is necessary for « 1) maintain shape « 2) counter osmotic pressures « 3) attachment sites for bacteriophages « 4) platform for surface appendages
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32 CELL WALL « 1) Maintaining the cell's characteristic shape © the rigid wall compensates for the flexibility of the phospholipid membrane and keeps the cell from assuming a spherical shape
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33 CELL WALL « 2) Countering the effects of osmotic pressure © the strength of the wall is responsible for keeping the cell from bursting when the intracellular osmolarity is much greater than the extracellular osmolarity
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34 CELL WALL « 3) Providing attachment sites for bacteriophages © teichoic acids attached to the outer surface of the wall are like landing pads for viruses that infect bacteria
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35 CELL WALL « 4) Providing a rigid platform for surface appendages © flagella, fimbriae, and pili all emanate from the wall and extend beyond it
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36 CELL WALL ª cell walls of all bacteria are not identical ª cell wall composition is one of the most important factors in bacterial species analysis and differentiation ª clinically « contributes to ability to cause disease « site of action of antibiotics ª There are two major types of walls: « Gram-positive « Gram-negative
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37 GRAM POSITIVE ª Has a thick peptidoglycan layer « 90% of the Gram-positive cell wall is comprised of peptidoglycan teichoic acids ª two types of teichoic acids
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38 GRAM POSITIVE ª 1) Lipoteichoic acid « on the surface, embedded in the peptidoglycan layer « linked to the cytoplasmic membrane
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39 GRAM POSITIVE ª 2) Wall teichoic acid « on the surface « linked to only the peptidoglycan layer
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40 GRAM POSITIVE
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41 ª cell wall of Gram-negative bacteria is much thinner « comprised of only 20% peptidoglycan ª have two unique regions which surround the outer plasma membrane: « periplasmic space « lipopolysaccharide layer GRAM NEGATIVE
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42 GRAM NEGATIVE ª a thin peptidoglycan layer ª an outer membrane attached to the peptidoglycan layer by lipoproteins
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43 GRAM NEGATIVE ª the outer membrane is made of protein, phospholipid and lipopolysaccharide « the lipid portion is embedded in the phospholipid « The lipid is toxic
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44 GRAM NEGATIVE « The cell wall has channels called Porins for the transport of low molecular weight substances
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45 GRAM NEGATIVE « periplasmic space © between the cytoplasmic membrane and the cell wall ¨ hydrolytic enzymes ¨ antibiotic inactivating enzymes ¨ transport proteins
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46 ª Strong negative charge assists in: « evading phagocytosis « evade the complement system ª provides increased barrier to: « antibiotics, lysozymes, detergents GRAM NEGATIVE
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47 ª provides more attachment sites for: « virus « harmful substances ª more susceptible to mechanical breakage ª lipid A endotoxin is toxic to host GRAM NEGATIVE
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48 CELL WALL ª the cell wall is not a regulatory structure like the cell membrane ª though it is porous, it is not selectively permeable and will let anything pass that can fit through its gaps
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49 EXTRACELLULAR MATRIX ª attached to the cell wall ª made of polysaccharide or polypeptide, or a combination of both ª form a viscous layer « capsule « slime layer
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50 CAPSULE ª Capsule « thick, structured and adheres strongly to the cell wall © Adhere to surfaces to form colonies © Antiphagocytic © Antigenic © Protect the organism from dehydration
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51 CAPSULE
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52 SLIME LAYER ª Slime layer « disorganized and loosely attached to the cell wall © Staphylococcus mutans ¨ causes dental caries
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53 MOVEMENT ª Flagellum « Made of the protein flagellin « rotation is for swimming towards an attractant « water is as viscous as syrup for a bacteria « able to move 50 microns/sec © 100X bacterial body length/sec © fish able to swim only 10X body length/sec
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54 MOVEMENT ª Axial Filaments « found in Spirochetes « similar to flagella « attached throughout the body length
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55 PILI ª made of the protein pilin ª virulence factors ª project from the cell surface ª Conjugation Pili « for the transfer of extrachromosomal DNA between donor and recipient
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56 FIMBRIAE ª used for attachment to surfaces ª more numerous than pili
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57 CYTOPLASMIC STRUCTURES ª Nucleoid « area of concentrated DNA « no nuclear membrane « The DNA is single circular « double stranded without proteins
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58 CYTOPLASMIC STRUCTURES ª Ribosomes « cytoplasmic, not attached to organelles ª Plasmids « Extrachromosomal loops of DNA © some code for drug resistance © toxins
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59 TYPICAL BACTERIA
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60 ENDOSPORES ª Metabolically inactive ª may produce endospores under environmental stress « lack of water « lack of nutrients « severe temperature changes © Clostridium © Bacillus
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61 ENDOSPORES ª Spores can be dormant for many years ª can survive « extreme heat « desiccation « radiation « toxic chemicals
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62 ENDOSPORES ª when conditions become favorable they revert to an active state ª Spore germination is activated by heat in the presence of moistures
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END CELL BIOLOGY OF BACTERIA
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