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Bacteria Chapter 24 Introduction • Believed to be the oldest form of life o Fossil evidence dates bacteria to 3.5 bya • Can live in all environments on earth o Deep ocean vents (archae) • High temp, high pressure, highly acidic o Extremely salty environments (archae) • Great salt lake, dead sea o Swamps/digestive tract (archae) • Produce methane gas o Others surround us at all times (bacteria/eubacteria) • Billions on your body at all time Classification • Broken into 5/6 kingdoms o Monera = archaebacteria and eubacteria • Microbiology uses 3 domains o Archae, bacteria, eukarya Kingdom • All bacteria are considered Monera o Includes bacteria and blue-green algae • Blue-green algae also called cyanobacteria • Archaebacteria (Domain Archaea) o “Ancient” bacteria o First broken off in 1977 • Eubacteria (Domain Bacteria) o “Modern” bacteria Prokaryotes • Lack membrane bound organelles o No membrane organelles = no nucleus • Single circular strand of DNA o Makes replication, transcription, translation occur much more rapidly Unicellular • All bacteria are unicellular • All prokaryotes are bacteria= all prokaryotes are unicellular • Not all unicellular are prokaryotes Phyla (3/1) • Schizophyta: common bacteria • Cyanophyta: Blue green algae o Responsible for formation of current atmosphere More Classification • Bacteria classification in large part determined by gram staining o Gram positive have a thick cell wall that absorbs purple dye o Gram negative have a thin cell wall, do not absorb dye and appear pink o Knowing if bacteria is gram +/- is important because of different succeptibilities to antibacterial drugs and disinfectants o Also release different toxins o Very useful tool tool for grouping bacteria Peptidoglycan • Material that absorbs the crystal violet • 20-80 nm in gram + o 90% of dry weight • 7-8 nm in gram – o 10% dry weight • Helps counter act osmotic pressure Characteristic Gram reaction Gram-positive Gram-negative Retain crystal violet dye Can be decolorized to accept and stain dark violet or counterstain (safranin); stain purple red Peptidoglycan layer Thick (multilayered) Thin (single-layered) Outer membrane Absent Present Flagellar structure 2 rings in basal body 4 rings in basal body Toxins produced Primarily exotoxins Primarily endotoxins Resistance to High physical disruption Low Resistance to drying High Low Linnaeus’s System of Classification • Due to enormous number of living things of all types a classification system was devised by a Swedish naturalist named Carrolus Linnaeus (1707-1778) • Used organisms morphology (structure and form) to categorize it Example of Levels of Classification • • • • • • • • Example Animalia Chordata Mammalia Carnivora Felidae Panthera Leo (Panthera Leo) • • • • • • • • Level Kingdom Phylum Class Order Family Genus Species Binomial Nomenclature • Scientific name of each organisms consist of 2 parts o Genus and species • Genus written first • Species written second o Examples • Homo (genus) sapien (species), panthera (genus) leo (species), panthera (genus) tigris (species) o Members of the same genus share many morphological similarities Methods of Getting Food • Heterotrophic o Unable to make organic molecules from inorganic molecules o Saprophytic bacteria • Autotrophic o Organisms that can make organic molecules for food o Chemosynthetic o Photosynthetic Types of Reproduction/Genetic Variation/Survival Adaptations • • • • • Binary Fission Endospores Conjugation Transformation Transduction Binary Fission • Simplest form of asexual reproduction • Parent cell split into two new cells o Offspring are exact copies o Very rapid Endospores • Help bacteria survive harsh conditions • Used by some gram positive bacteria • Protects the genetic information o Thick covering that is over the genetic info o Cell may die, but endospore can survive Transformation • DNA from dead bacteria is taken in by living bacteria • Living bacteria may take on traits of the dead ones • Major experiment done by Frederick Griffith (1928) Griffith’s Experiment Conjugation • Bacteria join and transfer genetic information Transduction • Virus transfers material between 2 bacterial cells Size of Bacterial Cells • Very small • Simple cells, do not require much material • Cell size measured in microns o o o o Also called micrometer mm 1 micron = 1/1 000 000 m 1 000 000 micron = 1m Size Scale Shape: Coccus (KOK-us) • Round or spherical • Plural term is cocci Shape: Bacillus (buh-SILLus) • Rod shaped • Plural is bacilli • Some are curved (comma shape) called vibrio Shape: Spirillum (spyRILL-um) • Spiral shaped • Plural is spirilla • Also called spirochetes Prefix: Diplo• 2 • 2 cells linked together Prefix: Strepto- (STREPtoh) • Twisted/chain • Many cells Prefix: Staphyl- (STAHfill-oh) • Cluster/bunch Structure of Bacterial Cells • All have o Rigid cell walls o Capsule – structure that surrounds cell wall o Genetic material- looks like a tangled bundle in the nuclear area • Some have o Plasmids-extra genetic information o 1 or more flagella- tail for movement (motile) o Pili – tiny hairs used for attachment Respiration: Aerobic • Process that requires oxygen to break down glucose • These bacteria are similar to mitochondria • Referred to as obligate aerobes o Must have oxygen gas available Respiration: Anaerobic • Energy produced without oxygen • Similar to the anaerobic process discussed earlier o Obligate anaerobes cannot be exposed to oxygen o Oxygen gas is actually a poison for them Respiration: Facultative Anaerobic Bacteria • • • • Can live in both types of conditions Do not use oxygen gas for energy production Oxygen gas is not a poison for them however E. Coli is an example of this o Lives in digestive tract (No O2) o Lives outside the digestive tract (21% O2) Life Style • Most Bacteria are… o Heterotrophic (very few autotrophic) o Saprophytic-live on dead organic material • Some bacteria are… o Parasites o In a symbiotic relationship: close association between 2 dissimilar organisms • Mutualism: both bacteria and host benefit Classified According To: • Size/shape • Structure of cell wall o Gram +/- • Whether or not they need oxygen • How they obtain food More Terms • Virulence – the ability to cause serious disease • Fermentation – production of alcohol/lactic acid • Pasteurization – a way to inhibit bacterial growth in some foods • Clostridium Botualinum – anaerobic bacteria that cause food poisoning (also used for Botox injections) • E. Coli (Escherichia Coli)– Human intestinal bacteria • Anthrax- related to Botualism (Bacillus anthracis) Bacterial Infections • Escherichia coli and Salmonella cause food poisoning. • Helicobacter pylori cause gastritis and ulcers. • Neisseria gonorrhoeae causes the sexually transmitted disease gonorrhea. • Neisseria meningitidis causes meningitis. • Staphylococcus aureus causes a variety of infections in the body, including boils, cellulitis, abscesses, wound infections, toxic shock syndrome, pneumonia, and food poisoning. • Streptococcal bacteria cause a variety of infections in the body, including pneumonia, ear infections, and strep throat. • Clostridium botulinum causes paralysis and decreased muscle tone. It is a weapons grade neurotoxin, what else is it used for? Diseases Importance of Monerans • Food Production o Buttermilk, cottage cheese, yogurt, sour cream, sauerkraut, pickles o Also cause food spoilage (milk, fruits, meats) • Recycle the remains of dead/decaying plants and animals • Fix/produce important gases in our atmosphere • Industrial chemical production • Clean up the environment • Genetic engeenring: because they are simple, unicellular, very few mutaions; we can study an predict genetic variablitiy Factors affecting growth • Temperature (39 degrees Celcius/79 degrees Fahrenheit) • Radiation (UV) • Chemicals (disinfectants/alcohol) • Available food • Available O2 • Prevention of Bacterial Refrigeration Growth o Slows reproduction • Boiling o Sterilizes • Pasteurizing food o High heat for a defined period of time, followed by rapid cooling • Drying o All living things need water • Salting o Similar to drying, will draw water out of bacterial cells • Canning Control of Bacterial Growth: Physical Agents • • • • • Dry Heat (passed through a flame) Moist heat/steam Boiling (100 degrees Celsius (212F) for 15 min Freezing: -20 C Radiation energy: UV light or x-rays Chemical Agents (Disinfectants) • Acid (low pH) or base (high pH) o All organisms have an optimal range for homeostasis • Alcohol: 70% isopropyl (rubbing alcohol) o Other types of alcohol work as well • Phenol lysol: Popular household cleaner • Detergents, or surfactants which are popular in antibacterial hand soaps Antibiotic Drugs • Grouped based upon their mode of action o Cell wall synthesis inhibitors (CWSI) • Penicillin o Ampicillin, Amoxicillian, and G and V • Cephalosporins o Keflex, Ceftin, Ceflex • Bacitracin o Used in ointments Protein Synthesis Inhibitors • PSI • Tetracycline o Used in treatment of acne/skin infections • Erythromycin o Derivative is Azithromycin o Come in a Z-pak • Known as zithromax o Clarithromycin • Known as biaxin Nucleic Acid Synthesis Inhib. • NASI • Cipro o Block synthesis of bacterial DNA o Only drug that can be used to treat inhalation anthrax Cell Metabolism Inhib. • CMI • Sulfa drugs o Synthetic antibiotics o Most other antibiotics produced form chemicals released by living organisms • Fungi and bacteria in most cases