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Chapter 19- Bacteria. I. Bacteria. A. Classifying Prokaryotes 1. Prokaryotes are organisms WITHOUT a nucleus. 2. Prokaryotes can be divided into Eubacteria and Archaebacteria. B. Eubacteria 1. The larger of the two kingdoms of prokaryotes is the Eubacteria.
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I. Bacteria A. Classifying Prokaryotes 1. Prokaryotes are organisms WITHOUT a nucleus. 2. Prokaryotes can be divided into Eubacteria and Archaebacteria.
B. Eubacteria 1. The larger of the two kingdoms of prokaryotes is the Eubacteria. 2. They live almost everywhere. 3. Usually surrounded by a cell wall the wall protects from injury and determines its shape.
4. The cell wall of Eubacteria contains peptidoglycan a carbohydrate. 5. Some even have a second membrane outside the cell membrane. This makes them VERY resistant to damage.
C. Archaebacteria 1. They lack a peptidoglycan and they have different membrane lipids. 2. The DNA sequences of Archae are more like Eukaryotes then prokaryotes. 3. Most live in extreme environment.
D. Identifying Prokaryotes 1. Prokaryotes are identical by characteristics such as shape, the chemical nature of their cell walls, the way they move and the way they obtain energy. 2. There are three different shapes of bacteria. Rod shaped Bacilli- Cocci Spirilla
3. Two different types of cell walls are found in Eubacteria. 4. Gram staining is used to tell them apart. 5. Gram-positive bacteria are purple, they have thicker walls. 6. Gram-negative bacteria are red or a light pink, they have thinner walls.
7. Some prokaryotes do not move at all. 8. Some glide, lash or have slime they secrete when they move.
E. Metabolic Diversity 1. Heterotrophs- must take in food. 2. Chemoheterotrophs take in organic molecules for energy and a supply of carbon.
3. We are Chemoheterotrophs. 4. Photoheterotrophs photosynthesize but also must obtain organic compounds. 5. Autotrophs make their own food.
6. Photoautotrophs use sunlight to make food. 7. Chemoautotrophs make food from carbon dioxide but not using the sun they make it by chemical reactions.
F. Releasing energy 1. Bacteria need a constant supply of energy. 2. Bacteria that need oxygen are called obligate aerobes. 3. Bacteria that DO NOT NEED oxygen, actually DIE if there is oxygen present are called obligate anaerobes.
4. Bacteria that can live with or without oxygen are called facultative anaerobes.
G. Growth and reproduction- bacteria reproduce three different ways. 1. Binary fission- Bacteria grows and grows and splits in half. Exact copes. 2. Conjugation- bacteria exchange genetic information.
3. Spore formation- when growth conditions become unfavorable many bacteria produce spores. a. One type of a spore is called an endospore. b. Spores can remain dormant for months. c. When conditions improve, the endospore will germinate and the bacterium will grow again.
H. Importance of bacteria 1. Bacteria are vital to maintaining the living world. 2. Some are producers that capture energy by photosynthesis. 3. Others are decomposers breaking down nutrients in dead matter.
4. Bacteria breakdown dead and decaying organisms. 5. Help to recycle nutrients – which helps to maintain equilibrium in the environment. 6. Bacteria also help perform critical steps in sewage treatment.
7. Others have human uses. 8. Bacteria convert nitrogen gas into a form plants can use, this is called nitrogen fixation. 9. Nitrogen fixation allows nitrogen atoms to continually cycle through the biosphere. 10. Bacteria are also used to make some foods such as: pickles, ice cream, yogurt, and other things.
II. Viruses A. What is a virus? 1. A typical virus is composed of a core DNA or RNA surrounded by a protein coat. 2. A virus’s protein coat is called its capsid.
3. The capsid includes proteins that enable a virus to enter a host cell. 4. Viruses that infect bacteria are called bacteriophages.
B. Viral infections 1. Once a virus is inside the host cell, two different processes may occur. 2. Lytic cycle- virus enters a cell, makes copies of it and causes the cell to burst.
3. Lysogenic infection- a virus integrates its DNA into the DNA of the host cell, and the viral genetic information replicates along with the hosts cell’s DNA. 4. The viral DNA that is embedded in the host’s DNA is called a prophage.
C. Retroviruses 1. Some viruses contain RNA as their genetic information and are called retroviruses. 2. When retroviruses infect a cell, they produce a DNA copy of their RNA.
3. The DNA is inserted into the host cell they will infect. 4. Retroviruses get their name because their genetic information is copied backwards. 5. Usually DNA-RNA, but retrovirus goes RNA-DNA
D. Viruses and living cells 1. Viruses must infect a living cell in order to grow and reproduce. 2. Are viruses alive?
III. Diseases A. Bacterial Disease in Humans 1. Disease causing agents are called pathogens. 2. Bacteria produce disease in one of two ways.
3. Some bacteria damage the cells and tissues of the infected organisms directly by breaking down the cells for food. 4. Other bacteria release toxins that travel throughout the body interfering with the normal activity of the host. 5. Tuberculosis- TB is inhaled into the lungs and destroys lung tissue.
6. Bacteria also release toxins in the body, like strep throat. 7. These toxins if go untreated could cause scarlet fever. 8. Diphtheria also infects the throat. It releases toxins and if it goes untreated could cause breathing problems, heart failure, paralysis and death.
9. A vaccine is a preparation of weakened or killed pathogens. 2 10. When injected into the body, the body will produce immunity to the disease. 11. Immunity is the body’s ability to destroy new pathogens.
12. Antibiotics are drugs that can attack and destroy the invading bacteria. 13. Bacterial diseases also affect animals. 14. There are various methods used to control bacteria growth- sterilization disinfectants and food processing.
15. Viruses produce disease by disrupting the body’s normal equilibrium. 16. Viruses attack and destroy certain cells in the body, causing the symptoms of the disease. 17. Many viruses infect plants also.
18. Many plants, like potatoes, tomatoes, apples and citrus fruits can be infected by viroids. 19. Viroids are single stranded RNA molecules that have no surrounding capsid.
20. Prions are short for protein infectious particles. 21. Mad cow disease is thought to be caused by Prions.
