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Transcript
Opening Activity Latin Root Word: archeo – • • • • • • • Food poisoning Bacterial Infection Acne Cavities Body Odor Antibiotics Break down food in our digestive system Intro To Bacteria I. Basic Bacteria Facts: • Microscopic/unicellular • Prokaryotic 0.25 µm Classification of Bacteria: Kingdom Archaebacteria: a) More ancient than eubacteria b) Peptidoglycan absent in cell walls III. Major Phyla of Bacteria: 1) Kingdom Archaebacteria: a) Methanogens live only in anaerobic conditions like swamps and sewage. b) Halophiles salt-loving c) Thermoacidophiles live in acidic and high temp. environments like hot springs and volcanic vents. II. Classifications of Bacteria: 1) Kingdom Eubacteria: a) Germs; account for most bacteria b) Can be divided into 12 phyla c) Cell walls contain peptidoglycan Shapes of Eubacteria: 1. bacilli rod-shaped 2. cocci sphere-shaped *streptococcichain *staphylococcigrape-like clusters 3. Spirilla spiral-shaped Eubacteria shapes cont. streptococcichain staphylococcigrape-like clusters Eubacteria • Heterotrophs • Photosynthetic autotrophs • Chemosynthetic autotrophs Eubacteria - Heterotrophs • Found everywhere • Parasites: live off of other organisms • Saprobes: live off of dead organisms or waste (recyclers) • Live symbiotically in the guts of animals or elsewhere in the bodies Photosynthetic Autotrophs • Photosynthetic: make their own food from light • Cyanobacteria – blue-green • Slimy stuff in ponds, streams, moist areas • Cyanobacteria were the first organisms to do modern photosynthesis and they made the first oxygen in the earth’s atmosphere Eubacteria: Chemosynthetic Autotrophs • Get energy by breaking down inorganic substances like sulfur and nitrogen • Make nitrogen in the air usable for plants – nitrogen fixing bacteria in roots of legumes III. Major Phyla of Bacteria: 1) Kingdom Eubacteria: a) Cyanobacteria (ex. blue-green algae) b) Spirochetes: spiral shaped (causes syphilis) c) Gram-positive bacteria (ex. Bacteria that cause strep; change milk to yogurt; produce antibiotics) d) Proteobacteria (ex. E. coli; nitrogen-fixing bacteria) Most Bacteria reproduce by one of 2 means: 1. Asexually – Also known as binary fission in which the chromosome replicates and then the cell divides – This produces 2 identical cells 2. Sexual Reproduction – Also known as conjugation in which genetic material is exchanged through cell-to-cell contact. One cell passes DNA to another. – This increases the genetic diversity of bacteria IV. Gram Stain: a) Laboratory technique used to group Eubacteria into two categories. b) Gram-positive eubacteria appear purple because of thicker layer of peptidoglycan. c) Gram-negative eubacteria appear pink because of thinner layer of peptidoglycan. I. Bacteria and Disease: A. Pathology: scientific study of disease B. Pathogens: bacteria that cause disease C. Famous Bacterial Diseases: Type of Disease Botulism Cholera Tooth Decay Gonorrhea Lyme Disease Rocky Mountain Spotted Fever Salmonella Strep throat Tetanus Tuberculosis Areas Affected nerves intestines teeth Urethra/ fal.tubes Skin, joints, heart Blood, skin Mode of Transmission intestines Respiratory tract nerves Lungs, bones, etc Contaminated food Sneezing/coughing Contaminated wounds coughing Improper preserved foods Contaminated water Bacteria in mouth Sexual contact Tick bite Tick bite D. Ways Bacteria Cause Disease: 1. Produce exotoxins (toxins made of protein and produced by Gram-positive bacteria). 2. Produce endotoxins (toxins made of carbohydrates and lipids and produced by Gram-negative bacteria; released when bacteria die). 3. Destroy body tissues by secreting digestive enzymes. Opening Activity: 3.2 • Latin Root Word: immun- Routes of Bacterial Infection • Respiratory tract • Gastrointestinal Tract • Genitourinary tract • Unnatural routes opened up by breaks in mucous membranes or skin Bacterial Evasion of Host Defense Mechanism • Four Steps in Bacterial Infection – Attachment to host cells – Proliferation – Invasion of host tissue – Toxin-induced damage to host cell Immune system • Two parts – Innate immune system (non-specific) – Adaptive immune system (specific) Nonspecific host resistance mechanisms Innate Immune system Immediate response physical barriers such as skin chemicals in the blood immune system cells that attack foreign cells in the body. Specific host Immune Response to Bacteria Adaptive Immunity immune cells (antibodies) specifically designed to attack that foreign cell includes a "memory" that makes future responses against a specific foreign cell more efficient. Contribution of the Immune Response to Bacterial Pathogenesis • Disease can also be caused by the immune response to the pathogen. • Pathogen-stimulated overproduction of cytokines can lead to symptoms of bacterial septic shock, and toxic shock syndrome. II. Antibiotics: A. Drugs that combat bacteria by interfering with cellular functions. B. Because humans overuse antibiotics, bacteria have built a resistance to those antibiotics. This is done through bacteria reproduction AND genetic recombination. Penicillin, an antibiotic, comes from molds of the genus Penicillium Notice the area of inhibition around the Penicillium. C. Common Antibiotics Antibiotic Penicillin Mechanism of Action Inhibits cell-wall synthesis Ampicillin Same as above Bacitracin Same as above Cephalosporin Same as above Tetracycline Inhibits protein synthesis Streptomycin Same as above Sulfa Drug Inhibits cell metabolism Rifampin Inhibits RNA synthesis Quinolines Inhibits DNA synthesis Target Bacteria Gram-Positive Broad spectrum G.P. G. P. Broad Spectrum G.N. meningitis G.P. AND G.N. Urinary tract Are all bacteria pathogens? • No, most are harmless • Some are even helpful – Examples of helpful bacteria: • Lactobacillus: makes cheese, yogurt, & buttermilk and produces vitamins in your intestine • Leuconostoc: makes pickles & sauerkraut • Pediococcus: makes pepperoni, salami, & summer sausage USDA NIFSI Food Safety in the Classroom© University of Tennessee, Knoxville 2006 A Closer Look – Helpful Bacteria www.bioweb.usu.edu Pediococcus - used in production of fermented meats Lactobacillus casei – found in human intestines and mouth to improve digestion Leuconostoc cremoris – used in the production of buttermilk and USDA NIFSI Food Safety in the Classroom© sour cream University of Tennessee, Knoxville 2006 Lactobacillus bulgaricus – used in the production of yogurt Helpful Bacteria • Decomposers help recycle nutrients into the soil for other organisms to grow • Bacteria grow in the stomach of a cow to break down grass and hay • Most are used to make antibiotics • Some bacteria help make insulin • Used to make industrial chemicals 40 Helpful Bacteria • Used to treat sewage Organic waste is consumed by the bacteria, used as nutrients by the bacteria, and is no longer present to produce odors, sludge, pollution, or unsightly mess. • foods like yogurt, cottage & Swiss cheese, sour cream, buttermilk are made from bacteria that grows in milk 41 Controlling Bacteria 3 ways to control bacteria: 1) Canning- the process of sealing food in airtight cans or jars after killing bacteria • endospores are killed during this process 2) Pasteurization- process of heating milk to kill harmful bacteria 3) Dehydration- removing water from food • Bacteria can’t grow when H2O is removed • example: uncooked noodles & cold cereal 42 Controlling Bacteria Antiseptic vs. Disinfectants Antiseptic- chemicals that kill bacteria on living things • means – “against infection” Examples: iodine, hydrogen peroxide, alcohol, soap, mouthwash Disinfectants- stronger chemicals that destroy bacteria on objects or nonliving things 43 Drawing Bacterial Structure • Cell Wall - outermost structure of the cell. • Made up of a substance called peptidoglycan Bacterial Structure Continued • Capsule: This is a layer of slime secreted over the cell wall of the bacterium. • The capsule provides protection • Most pathogenic bacteria are encapsulated. Bacterial Structure Continued • Flagella - whip - like structures that propel the bacteria I. Common Structures/Functions of Bacteria: Structure Cell Wall Outer Membrane Cell Membrane Cytoplasm Chromosome Plasmid Capsule and slime layer Endospore Pili Flagellum Function Protects cell; gives it shape Only in G.N.; protects against antibiotics Important in cell respiration Contains DNA/ribosomes Carries genetic info.; single loop of DNA Carries extra genes from genetic recom. Protects cell; helps attach to other surfaces (glycocalyx) Only in G.P.; survival in harsh conditions Helps attach to other surfaces Cell movement 3. Spore Formation • When living conditions become unfavorable, some bacteria can form dehydrated cells known as endospores • Endospores have thick walls and can resist heat, drought and radiation and thus they can survive harsh conditions Endospore • When conditions improve, the spore will germinate and bacteria will grow again III. Bacteria in the Environment: Type Environment Obligate Anaerobes CANNOT live with oxygen Facultative Anaerobes Can live WITH or WITHOUT oxygen Obligate Aerobes CANNOT live without oxygen “Thermophilic” Grow best in HIGH temperatures Opening Activity • Greek Root Word: anti-