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Transcript
Bacteria Chapter 24 Introduction Believed to be the oldest form of life Fossil evidence dates bacteria to 3.5 bya Can live in all environments on earth Deep ocean vents (archae) Extremely salty environments (archae) Great salt lake, dead sea Swamps/digestive tract (archae) High temp, high pressure, highly acidic Produce methane gas Others surround us at all times (bacteria/eubacteria) Billions on your body at all time Classification Broken into 5/6 kingdoms Monera = archaebacteria and eubacteria Microbiology uses 3 domains Archae, bacteria, eukarya Kingdom All bacteria are considered Monera Includes bacteria and blue-green algae Archaebacteria (Domain Archaea) Blue-green algae also called cyanobacteria “Ancient” bacteria First broken off in 1977 Eubacteria (Domain Bacteria) “Modern” bacteria Prokaryotes Lack membrane bound organelles No membrane organelles = no nucleus Single circular strand of DNA 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 Schizophyta: common bacteria Cyanophyta: Blue green algae Responsible for formation of current atmosphere More Classification Bacteria classification in large part determined by gram staining Gram positive have a thick cell wall that absorbs purple dye Gram negative have a thin cell wall, do not absorb dye and appear pink Knowing if bacteria is gram +/- is important because of different succeptibilities to antibacterial drugs and disinfectants Also release different toxins Very useful tool tool for grouping bacteria 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 Level Kingdom Phylum Class Order Family Genus Species Example Animalia Chordata Mammalia Carnivora Felidae Panthera Leo (Panthera Leo) Binomial Nomenclature Scientific name of each organisms consist of 2 parts Genus and species Examples Genus written first Species written second Homo (genus) sapien (species), panthera (genus) leo (species), panthera (genus) tigris (species) Members of the same genus share many morphological similarities Methods of Getting Food Heterotrophic Unable to make organic molecules from inorganic molecules Saprophytic bacteria Autotrophic Organisms that can make organic molecules for food Chemosynthetic 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 Offspring are exact copies Very rapid Endospores Help bacteria survive harsh conditions Used by some gram positive bacteria Protects the genetic information Thick covering that is over the genetic info 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 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-SILL-us) Rod shaped Plural is bacilli Some are curved (comma shape) called vibrio Shape: Spirillum (spy-RILL-um) Spiral shaped Plural is spirilla Also called spirochetes Prefix: Diplo 2 2 cells linked together Prefix: Strepto- (STREP-toh) Twisted/chain Many cells Prefix: Staphyl- (STAH-fill-oh) Cluster/bunch Structure of Bacterial Cells All have Rigid cell walls Capsule – structure that surrounds cell wall Genetic material- looks like a tangled bundle in the nuclear area Some have Plasmids-extra genetic information 1 or more flagella- tail for movement (motile) 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 Must have oxygen gas available Respiration: Anaerobic Energy produced without oxygen Similar to the anaerobic process discussed earlier Obligate anaerobes cannot be exposed to oxygen 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 Lives in digestive tract (No O2) Lives outside the digestive tract (21% O2) Life Style Most Bacteria are… Heterotrophic (very few autotrophic) Saprophytic-live on dead organic material Some bacteria are… Parasites 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 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) Diseases Importance of Monerans Food Production Buttermilk, cottage cheese, yogurt, sour cream, sauerkraut, pickles 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 Growth Refrigeration Boiling All living things need water Salting High heat for a defined period of time, followed by rapid cooling Drying Sterilizes Pasteurizing food Slows reproduction 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) Alcohol: 70% isopropyl (rubbing alcohol) All organisms have an optimal range for homeostasis 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 Cell wall synthesis inhibitors (CWSI) Penicillin Cephalosporins Ampicillin, Amoxicillian, and G and V Keflex, Ceftin, Ceflex Bacitracin Used in ointments Protein Synthesis Inhibitors PSI Tetracycline Used in treatment of acne/skin infections Erythromycin Derivative is Azithromycin Come in a Z-pak Known as zithromax Clarithromycin Known as biaxin Nucleic Acid Synthesis Inhib. NASI Cipro Block synthesis of bacterial DNA Only drug that can be used to treat inhalation anthrax Cell Metabolism Inhib. CMI Sulfa drugs Synthetic antibiotics Most other antibiotics produced form chemicals released by living organisms Fungi and bacteria in most cases