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Bacteria and Viruses Chapter 19 Taxonomy • The branch of biology dealing with the classification of life. • 1700s 2 kingdoms: plant and animal • 1800s 3 kingdoms: plant, animal, and protista • 1950-1990s 5 kingdoms: plant, animal, protista, fungi, monera • Present: 6 kingdoms: eubacteria, archaebacteria, protista, animal, plant, fungi Prokaryotes • Traditionally all prokaryotes were classified as Monerans Gr. 1. Single or one • Also known as bacteria (p.) or bacterium (s.) • Presently, the prokaryotes are divided into two kingdoms. 1. K. Eubacteria • Larger of the two kingdoms • Live almost everywhere • Vital for life functions and industry • Both helpful and harmful 2. K. Archaebacteria • Comes from the Greek word archaio which means “ancient” • Believed by many to be the earliest organisms to inhabit the earth • All live in harsh environments • 3 separate phyla: 1. Methane-producing bacteria (methanogens) • Intestinal tracts of animals • Bottoms of swamps • Used for sewage treatment 2. Salt-loving bacteria (Halophiles) • Thrive in high salinity waters where no other life can exist. • Great Salt Lake • Dead Sea 3. Hot-acidic loving (thermoacidophiles) • Thrive at temperatures as great as 180ºF and pHs as low as 2. • Natural springs. • Yellowstone National Park Facts about bacteria: • Found everywhere • Very small. Much smaller than any cell in our body. • No membrane-bound structures or nucleus. (prokaryotes) • Usually surrounded by a cell wall and a capsule for additional protection. General structure: Classification according to shape. 1. Coccus (spherical) Can be single cells Pairs Chains example Strep throat Bacillus (rod) • Single cells • Pairs • Chains 2. • example – anthrax 3. Spirillum(spiral) Only exist as single cells Example: cholera, syphillis Shapes: Gram-positive bacteria • Chemical nature of cell wall allows these bacteria to retain the violet stain. • Can be harmed by antibiotics like penicillin • example: streptococcus Gram-negative bacteria • More difficult to penetrate cell wall. • Usually more difficult to treat with antibiotics • Example: E-coli Movement • Usually move through flagella or gliding along a surface. • Surface Structures Metabolic Needs • Anaerobic • Aerobic • Cannot live in the • The most presence of common type oxygen • Gets energy • Cannot live through without oxygen fermentation (CO2) Heterotrophic bacteria • Saprobes • Parasites • Feed off the • Live on or in remains of other living dead plants and organisms. animals. Often cause Seldom cause disease disease Autotrophic bacteria • Photoautotroph • Chemoautotroph • Use sunlight to convert carbon dioxide into energy • Ex. cyanobacteria • Use inorganic chemical compounds to convert carbon dioxide into energy. Genetic material • Nucleoid= a single circular chromosome containing the DNA and RNA. • Endospore = tough protective coat that covers and protects the nuclear material. Reproduction • All reproduce asexually • Usually through binary fission • Under certain conditions, bacteria can reproduce very quickly – A small colony can double in 20 minutes. – animation Binary fission • The most common type of asexual reproduction. • A single cell splits to form two daughter cells Exchange of DNA Conjugation = genes move from one cell to another Endospores • A thick covering around the DNA that allows the bacterium to remain dormant for long periods of time. If necessary, many years. Helpful bacteria • • • • • Decompose food wastes Produce vitamins Produce antibodies Genetic engineering Decomposition of dead plants and animals • Industry & agriculture Plant roots • Found on the roots of plants. • Can be helpful in ‘fixing’ nitrogen for plant use. • Rhizobium nodules on roots of soybeans • Are they living or non-living? • Contain genetic material • Lack organelles Cannot reproduce unless inside a host cell. • The word virus comes from the Greek word for POISON • Cause many diseases. How big is a virus? • Much smaller than bacterial cells. • Scientists have only recently, last 60 years, learned anything about viruses • Classified according to the types of cells they attack. Virus structure: • A center core of DNA or RNA surrounded by a protein coat called a capsid. 2 main types of viral reproduction: • LYTIC CYCLE 1. Injects its nucleic acid (DNA or RNA) into the cell to take over cellular activities. • LYSOGENIC CYCLE 1. Coexists with the cell without destroying the host cell Lytic cycle Lysogenic cycle • Direct the production of proteins by the host cell. • RETROVIRUS = A special type of virus that can make DNA which will produce new RNA, which, in turn, makes proteins that produce new viruses. • Ex. Diseases caused by microorganisms: • Pathogens: disease-causing agents • BACTERIAL DISEASE: 1) Damage cells and tissues directly 2) Release toxins to interfere with normal cellular activity Common bacterial diseases: • Lyme disease • Tetanus • Strep throat • Tuberculosis • E. coli poisoning Controlling bacterial disease. • ANTIBIOTICS • 1928. Discovery of penicillin by Sir Alexander Flemming • Came from a mold. Common methods of bacterial infection. • Food & water (E. coli) • Coughing & sneezing • Sexually transmitted. • Carried by insects Food disease prevention • Keep hands, and cooking utensils clean • Canning and preservation techniques with food. • Pasteurization • Freezing How do we prevent viral diseases? • Cannot be treated with ordinary antibiotics • Vaccinations. The word comes from the vacca Latin for “cow”. • A vaccine is a weakened form of a virus that is used to stimulate the immune system to produce antiviral substances. Edward Jenner (17491823) • British physician • Developed the first vaccine in 1798 for the viral disease smallpox. • Considered the “Father of Immunology” Common viral diseases: • • • • • • • • AIDS Measles Chickenpox Smallpox Influenza The common cold West Nile Polio • Viral disease that is believed to have originated in Egypt at least 2000 years ago. • Characterized by pox lesions and boils. • Spread to the Americas by Spanish conquistadors. • Jenner’s vaccine was developed after observing a bovine disease: “cowpox” Eradication of smallpox: • In 1967 the World Health Organization launched a global effort to eradicate smallpox. • 1978 : Last known case of smallpox. • 1980 : W.H.O. declares the world free of smallpox. • Is there any smallpox virus left? Viroids and Prions • Viroid • Small disease causing particle. • Affect plants • Prion • Small disease causing particle. • Affects animals. • example: Assignment: • Pages 493 • 1-10,11,12,13,19,22,23,24 • Page 495 • 1-12