Bacteria Structure and Function 1 Prokaryote Eukaryote Evolution
Bacteria Structure and Function 1
Prokaryote & Eukaryote Evolution 2
Cellular Evolution • Current evidence indicates that eukaryotes evolved from prokaryotes between 1 and 1. 5 billion years ago • Two theories: 1. Infolding theory 2. Endosymbiotic theory 3
Infolding Theory • The infolding of the prokaryotic plasma membrane gave rise to eukaryotic organelles. infolding organelle 4
Endosymbiotic Theory • Endosymbiosis refers to one species living within another(the host) • Movement of smaller photosynthetic & heterotrophic prokaryotes into larger prokaryotic host cells chloroplast • Formed cell organelles mitochondria 5
Prokaryotic & Eukaryotic Cells 6
Earliest Prokaryotes • Most numerous organisms on Earth • Include all bacteria • Earliest fossils date 2. 5 billion years old 7
Classification of Life 8
Three Domains of Life • Archaea – prokaryotes living in extreme habitats • Bacteria. Cyanobacteria and eubacteria • Eukarya – Protozoans, fungi, plants, & animals 9
Kingdoms of Bacteria Archaebacteria: ü Found in harsh environments ü Undersea volcanic vents, acidic hot springs, salty water 10
Archaebacteria 11
Kingdoms of Bacteria Eubacteria: ü Called the true bacteria ü Most bacteria are in this group ü Include photosynthetic Cyanobacteria 12
Eubacteria 13
Characteristics of Bacteria 14
Bacterial Structure • • Microscopic prokaryotes No nucleus or membranebound organelles Contain ribosomes Single, circular chromosome in nucleoid region 15
Bacterial Cell 16
Protection • Cell Wall made of Peptidoglycan • May have a sticky coating called the Capsule for attachment to host or other bacteria 17
Sticky Bacterial Capsule 18
Bacterial Structure PLASMIDS • Have small rings of DNA called Plasmids • Unicellular • Small in size (0. 5 to 2μm) 19
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Bacterial Structure • Infoldings of cell membrane carry on photosynthesis & cellular respiration • Infoldings called Mesosomes 21
Mesosomes MESOSOME 22
Bacterial Structure • Most grow best at p. H of 6. 5 to 7. 0 • Many act as decomposers recycling nutrients • Some cause disease 23
Staphylococcus Bacterial 24
Useful Bacteria • Some bacteria can degrade oil • Used to clean up oil spills 25
Useful Bacteria • Other uses for bacteria include making yogurt, cheese, and buttermilk. 26
Flagella • Bacteria that are motile have appendages called flagella • Attached by Basal Body • A bacteria can have one or many flagella 27
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Flagella • Made of Flagellin • Used for Classification • Monotrichous: 1 flagella • Lophotrichous: tuft at one end • Amphitrichous: tuft at both ends • Peritrichous: all around bacteria 29
Monotrichous Lophotrichous Amphitrichous Peritrichous 30
Question: What is this type of bacteria ? 31
Pili • • • Short protein appendages Smaller than flagella Adhere bacteria to surfaces • Used in conjugation for Exchange of genetic information • Aid Flotation by increasing buoyancy 32
Pili in Conjugation 33
Bacterial Shapes 34
Shapes Are Used to Classify • Bacillus: Rod shaped • Coccus: Spherical (round) • Vibrio: Comma shaped with flagella • Spirillum: Spiral shape • Spirochete: wormlike spiral shape 35
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Grouping of Bacteria • Diplo- Groups of two • Strepto- chains • Staphylo- Grapelike clusters 37
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Diplococcus 40
Streptococcus Causes Strep Throat 41
Staphylococcus 42
Bacillus - E. coli 43
Streptobacilli 44
Spirillum 45
Spirochetes 46
Leptospira 47
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Bacterial Kingdoms 49
Archaebacteria • Lack peptidoglycan in cell walls • Have different lipids in their cell membrane 50
Archaebacteria • Archaebacteria can live in extremely harsh environments 51
Archaebacteria • Subdivided into 3 groups: 52
Methanogens • Live in anaerobic environments (no oxygen) • Get energy by changing H 2 & CO 2 into methane gas 53
Methanogens • Break down cellulose in a cow’s stomach • Produce marsh (methane) gas 54
Extreme Halophiles • Live in very salty water • Use salt to generate ATP (energy) 55
Thermoacidophiles or Thermophiles • Live in extremely hot environments 56
Kingdom Eubacteria True Bacteria 57
Characteristics • 3 basic shapes (coccus, bacillus, spirilla) • Most are heterotrophic (can’t make their own food) 58
Gram Staining • Developed in 1884 by Hans Gram 59
Gram Positive • Have thick layer of peptidoglycan (protein-sugar complex) • Single lipid layer 60
Gram Positive Bacteria ü Lactobacilli (makes yogurt & buttermilk) ü Actinomycetes (make antibiotics) 61
Gram Negative Bacteria • Thin layer of peptidoglycan in cell wall • Extra thick layer of lipids 62
Gram Negative • Rhizobacteria grow in root nodules of legumes (soybeans, peanuts) 63
Gram Negative • Rickettsiae are parasitic bacteria carried by ticks 64
Cyanobacteria • Gram negative • Photosynthetic • Called blue-green bacteria 65
Cyanobacteria • May be red, yellow, brown, black, or blue-green • May grow in chains (Oscillatoria) • Have Heterocysts to help fix N 2 66
Cyanobacteria 67
Spirochetes • Gram positive • Flagella at each end • Move in corkscrew motion 68
Enteric Bacteria • Gram negative • Can live in aerobic & anaerobic habitats 69
Chemoautotrophs • • Gram negative Obtain energy from minerals like iron 70
Nutrition, Respiration, and Reproduction 71
Modes of Nutrition • Saprobes – feed on dead organic matter • Parasites – feed on a host cell 72
Methods of Respiration • Obligate Aerobes – require O 2 (tuberculosis bacteria) • Obligate Anaerobes – die if O 2 is present (tetanus) 73
Bacterial Respiration • Anaerobes carry on fermentation 74
Reproduction • Bacteria reproduce asexually by binary fission • Single chromosome replicates & then cell divides 75
Cellular organism copies it’s genetic information then splits into two identical daughter cells 76
Binary Fission E. coli 77
Reproduction • Bacteria reproduce sexually by Conjugation • Form a tube between 2 bacteria to exchange genetic material 78
Conjugation 79
Spore Formation • Form endospore whenever when habitat conditions become harsh (little food) 80
Transduction & Transformation • Genetically change bacteria • May become antibiotic resistant 81
Pathenogenic Bacteria 82
Pathogens • Called germs or microbes • Cause disease 83
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