MA+Immune+System+HW

PATHOGENS 1. What is a pathogen? 2. What are the body's three lines of defense against pathogens? 3. Write a one paragraph summary of bacteria. Bacteria are singe-celled prokaryotes, which means they don't have a nucleus. Bacteria's cell wall is made of amino acids(protein). Some cell walls of bacteria are covered with a thick "capsule". This outline helps bacteria cling onto things(like teeth) and also protects bacteria from being attacked by white blood cells. Bacteria have flagellum which are attached to bacteria and helps them move backward. Some bacteria can attach onto host cells with something called fimbriae. Some bacteria have a pilus which passes DNA. The pilus is hollow in structure. Bacteria reproduce during binary fission. The chromosome attached to the plasma membrane is copied and then the chromosomes seperate as the cell gets bigger. Bacteria can reproduce very fast if in the right conditions. Types of bacteria are strep throat, turberculosis, food poisoning, and gonorrhea. 4. Write a one paragraph summary of viruses. A virus needs something living to be active and reproduce. Viruses are not made of cells. Viruses are parasites that cause colds, flus, AIDS, genital warts, and herpes. A virus is much smaller than bacteria and has two parts. One part is the outer capsid which is made of proteins and the inner part that is nucleic acid. Viruses don't need double sided DNA to reproduce. A virus finds and attaches to a host with a lock and key method, it locks and then its nucleic information is entered into the cell. A virus may be able to reproduce within a cell and then exit the cell. Viruses can be passed along through animals or insects. 5. What is an emerging virus? IMMUNE SYSTEM 6. What is an antibody? What do they do? 7. What is B Cell? 8. What is a Cytotoxic T Cell? 9. What is a Helper T Cell? 10. What is an antigen? How does the body respond to an antigen?
 * A pathogen is a bacteria or virus that causes human infectious diseases.
 * 1) Barriers to entry: skin, mucous membranes in openings(like the nose), mucous and skin keep pathogens from entering the body
 * 2) first responders: white blood cells prevent an infection if a pathogen enters
 * 3) specific defenses kill an infection...these also protect us from cancer
 * An emerging virus is a new virus.
 * An antibody is a protein that combines with antigens( proteins that are foreign) and mark them for destruction. An antibody usually is y shaped and has two binding sites for a certain antigen.
 * A b cell produce plasma cells and memory cells. They recognize antigen and then undergo clonal selection. Clonal expansion produces antibody-secreting plasma cells as well as memory B cells. Memory B cells usually stay in the body so if the same antigen comes back it can be ready to fight it again.
 * T Cells regulate immune response; produce cytotoxic T cells and helper T cells. T cells also undergo clonal expansion. After diseases are fought T cells will be left behind if it comes back. These cells kill virus infected cells.
 * A helper t cell regulates immunity by producing cytokines and stimulating other immune cells.
 * An antigen is a foreign object that is usually a protein. They are fought with antibodies, b cells, and t cells.