4 I. Viruses A. Is a virus a living organism? 1. All living things are made of cells, able to grow and reproduce. 2. A virus IS able to do these things but ONLY inside a host cell. 3. Viruses cause diseases in many organisms.
5 B. Discovery of viruses 1. At the end of the 19 th century scientists were trying to find the cause of tobacco mosaic disease (TMV). 2. In 1935 Wendell Stanley isolated this virus.
7 C. A virus’s Shape is determined by its parts C. A virus’s Shape is determined by its parts 1. The virus protein coat, or capsid, may contain either RNA or DNA but NOT both. 2. RNA viruses include HIV, which causes AIDS, influenza viruses and rabies virus.
9 3. DNA viruses include those viruses that cause warts, chickenpox and mononucleosis. 4. Many viruses have a membrane or an envelope that surrounds the capsid. 5. The envelope helps the virus enter cells.
10 6. It consists of proteins, lipids, and glycoproteins. 7. Viruses that infect bacteria, called bacteriophages, have a complicated structure. 8. A bacteriophage has capsid and a tail.
11 9. Viruses replicate inside living cells 10. Viruses cause damage when the viruses replicate inside the cells. 11. Any agent that causes disease is called a pathogen.
12 D. Lytic cycle 1. Virus attaches to a cell and injects DNA. 2. Viral DNA enters the Lytic cycle. 3. New Viruses are made. 4. Cell breaks open and releases viruses. (destroying the host cells.)
14 E. Lysogenic cycle 1. Virus attaches to a cell and inject DNA. 2. Viral DNA enters the Lysogenic cycle. 3. Viral DNA integrates with host DNA. 4. The host cell divides normally 4. The host cell divides normally
15 5. Many cell divisions. 6. The provirus may enter the Lytic cycle, or stay dominant. 7. Then the DNA enters the Lytic cycle. 8. New viruses are made. 9. Cell breaks open and releases viruses
16 4. Viruses have a major impact on the living world.
18 F. Viruses are host cell specific 1. Viruses are often restricted to certain kinds of cells. 2. Some will affect plants and some will affect animals.
19 G. HIV can replicate in your cells 1. Acquired immunodeficiency syndrome (AIDS) is a disease in which an individual is unable to defend his or her own body against infections. 2. The HIV causes AIDS.
20 3. HIV – infected people do not develop AIDS symptoms until years after infection. 4. HIV infected individuals can feel healthy and still spread the virus to others. 5. It is transmitted in body fluids, such as semen and vaginal fluid.
21 H. Viruses cause many diseases 11. Diseases caused by viruses have been known and feared for thousands of years. 2. 22 million people died of the flu during 1918-1919. 3. Viruses that evolve are called emerging viruses.
22 4. These new pathogens are dangerous to public health. 5. Prions are particles that are composed of proteins and have no nucleic acids. 6. Prions are infectious even though they contain no genes.
23 7. Prions were first linked to a sheep disease called scrapie. 8. This also causes mad cow disease. 9. A viroid is a single strand of RNA that has no capsid. 10. They affect plants like cucumbers, potatoes, avocados, and oranges.
24 II. Bacteria A. Bacteria have a simpler structure than Eukaryotes. 1. Bacteria are prokaryotes they do not have a nucleus. 2. Bacteria are small!- 3. Bacteria have only one cell. 4. Bacteria have one single circular DNA.
25 5. Bacteria reproduce by binary fission. 6. Bacteria have flagella that move them around. 7. Bacteria have many different types of metabolic activities.
26 A. The structure 1. A bacterial cell has three shapes. Bacillus- rod shaped Bacillus- rod shaped Coccus- round shaped Coccus- round shaped Spirillum- spiral shaped
28 2. Bacteria can have two types of cell walls, you can tell this by gram staining. 3. Gram staining is important in medicine because the two groups of bacteria differ in how they respond to antibiotics. 4. Some bacteria form thick walled endospores around their chromosomes and a small bit of cytoplasm when they are exposed to harsh conditions.
29 5. Pili enable bacteria to stick to stuff like your skin. 6. Conjugation is a process in which tow organisms exchange genetic material.
30 C. Bacteria are grouped according to how they obtain energy 1. Photosynthetic bacteria- bacteria that is able to make food from the sunlight. They must live in an anaerobic (oxygen free) environments.
31 2. Chemoautotrophic bacteria- they obtain energy by chemically removing electrons from material. 3. Heterotrophic bacteria- feed on organic material and other organisms. They are aerobic, they need oxygen.
32 D. Bacteria cause disease in two basic ways 1. Bacteria can metabolize their host. They take all the nutrients from the host. Example- TB 2. Bacteria can cause toxins. Example botulism
33 3. Bacterial disease can be fought 4. Antibiotics- fight bacterial infection.
34 E. Bacteria are important 1. Food and chemical production- many foods we eat are processed by specific kinds of bacteria examples- pickles, buttermilk, cheese, sauerkraut, olives, vinegar, sourdough bread and some sausages. 2. Mining and environmental uses of bacteria