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Transcript
Unit 6 notes Viruses and Immune System What is a Virus? - Infectious particle made of only a strand of DNA or RNA surrounded by a protein coat - Cannot reproduce on their own - Size: 50- 200nm What is a prion? - Infectious particle made only of a protein that can cause other proteins to fold incorrectly. - NO GENETIC MATERIAL - Size: 2-10nm What is a viroid? - Infectious particles that cause diseases in plants. Single stranded RNA without a protein coat. Passed through seeds or pollen Can stunt the growth of plants Size: 5-150 nm 18.2 Viral structure and reproduction MAIN IDEA Tobacco Mosaic Virus SUPPORTING DETAILS - Researched by Dmitri Ivanovsky - Thought the disease was caused by bacterium - Filtered extract of diseased leaves through pores small enough to filter out bacteria but still found extracts of the disease - Martinus Beijerinck passed the disease causing agent through an agar gel and proposed this is what caused the disease - Name them viruses, which is Latin for “poison” Structure of viruses - A single viral particle is called a virion - The genetic material is surrounded by a protein shell called a capsid - May have a protective outer layer called a lipid envelop - This can have glycoproteins attached to the outer layer Enveloped Virus Ex: Influenza Helical Virus Ex: Rabies Polyhedral Virus Ex: Foot and Mouth Disease Lytic and Lysogenic Cycle (Page 516) Know this very well 18.3 Viral Diseases Main Idea First Defenses Supporting Details - 1st obstacle a virus must get through is the skin, outer skeleton, or cell wall of an organism - Can penetrate the skin through a cut or a scrape. Or it can enter through a mucous membrane - Most common points of entry are the mouth, nose, genital area, eyes, or ears Types of infections Example of viral infection Common Cold Influenza (Flu) SARS ( Severe Acute Respiratory Details - Over 200 viruses can cause this - Can mutate as it goes from one person to another - Last about a week - Spreads quickly and can become a local epidemic - Infects about 20% of Americans each year - 3 subtypes effect humans - Can jump from one species to another (Bird flu effecting humans) - Very similar to the flu - 1st appeared in Asia in 2002 - Spread quickly and became a pandemic - Has been very rare since 2003 - Retrovirus - Takes RNA and makes DNA through reverse transcriptase - Infects the host as a Lysogenic infection - Becomes Lytic as it kills WBC - Very high mutation rate Syndrome) HIV (Human Immunodeficiency Virus Vaccines Definition: A substance that stimulates the body’s own immune response against invasion by microbes How do they work: Will cause the body to have an immune response against the weakened virus that has entered the organism. This will allow the organism to fight off a true attack How are they made: Made from a pathogen of the same virus that is weakened Examples of disease that have vaccines: - Chicken Pox - Hepatitis A - Mumps - Rabies - Flue REMEMBER THAT A VIRUS IS THE ONLY THING THAT A VACCINE WILL AFFECT. THEY CAN NOT EFFECT BACTERIA. 18.4 Bacteria and Archaea Plasmid- Small piece of genetic material that can replicate separately from the prokaryote’s main chromosome Cell Wall- Barrier for the organism from the outside world. Very rigid Chromosome- Contains the bacteria’s DNA Plasma Membrane- Flexible barrier that helps regulate what enters and exits the organism Pili- Helps organism to stick surfaces and other organism Flagellum- Whip-like structure that helps the organism to move Be able to label these parts of a bacteria and tell the function to illustration is on page 523 18.6 Bacterial Diseases and Antibiotic WAYS BACTERIA CAUSE ILLNESS TO A HOST 1. By invading tissues and attacking cells. - Tuberculosis- invades host WBC and kills them 2. Making poisons/ and toxins -Ex. Staphylococcus aureus and Clostridium botulinum Staph can’t be destroyed by high temps and usually isn’t fatal C. botulinum caused by endospores in canned food and can be fatal MAIN IDEA Antibiotics are used to fight bacterial disease SUPPORTING DETAILS - Viruses cannot be treated with antibiotics - Bacteria can be treated with antibiotics - Antibiotics are chemicals that slow or stop the growth of bacteria by destroying the cell wall - Can be produced naturally from bacteria or fungi - Do not harm animals b/c no cell wall and that is why viruses are not effected as well - Antibiotics if abused can cause sickness by wiping out colonies of intestinal microbes CAUSE OF ANTIBIOTIC RESISTANCE OVERUSE: Create a selective pressure that benefits the bacteria they are trying to destroy. Bacteria will become resistant UNDERUSE: Leads to drug resistance, only kills the weakest bacteria. In doing this, the strongest bacterial become resistant MISUSE: Used to help animals grow larger. Bacteria and pathogens can become resistant to this Antibiotics are not the primary way to treat bacterial infections. The best way to treat infections is by preventions. Take care of your body and you will notice you less sick.