Biology: Defense Against Disease Review
Explain the difference between active immunity and passive immunity and give an example of each.
Active immunity is where you make the antibodies. You're exposed to a pathogen (antigen) and your body starts making antibodies against it. Example is vaccines. Passive is where something else makes the antibodies and it is given to you. With this you don't have the memory cells to fight it another time. This is a treatment, like injected the blood of someone with the antibodies Immunity: having sufficient biological defenses against infection - Active immunity: due to the production of antibodies by the organisms itself after the immune response has been stimulated by a pathogen *Natural: exposure to infectious agents, like the chicken pox immunity *Artificial: immunization, like the MMR vaccine - Passive immunity: the acquisition of antibodies from other organisms, in which active immunity has been stimulated. *Natural maternal antibodies, such as colostrum in the placenta *Artificial: antibodies from other sources, such as rabies treatment
Define antibiotic
Antibiotic: a chemical/drug that inhibits the growth of microorganisms, mostly antibacterial. Block processes in prokaryotes and kill bacteria inside the body. Treats and prevents prokaryotic bacteria. Don't affect viruses
Define antibody
Antibody: a specific immune response to antigens on a pathogen by binding to the pathogen. They are globular proteins
Define antigen
Antigen: Any chemical that stimulates an immune response. A protein/molecule on the surface of pathogens that are recognized as foreign by the body and stimulate a specific immune response through antibody formation
Explain the events leading to the production of antibodies? Which cells are involved in the process?
B cells are very specific. Phagocytes are nonspecific. Antibodies are a form of specific immune response - Antigens, which are found on the surface of viruses and other pathogens, cause antibody formation, or a protein that recognizes specific antigens and binds to it for immune response - Lymphocytes all recognize one specific antigen, causing it to make clones of itself and producing many antibodies, called clonal selection. Some cloned cells stay as memory cells, ready for a second invasion. - The antibodies fight the pathogen by making it more recognizable for phagocytes to engulf and preventing viruses from infesting host cells Specifically: - Can either be active immunity or passive - Pathogen enters the blood - It is engulfed by a macrophage through endocytosis - Antigen from the bacteria goes to the surface of the phagocyte, which is presented to a helper T cell - The helper T cell activates B-cells and killer T cells specific to that antigen - The B cell matches its receptors to the antigen and it fully activated by the helper T-cell - The B cell divides and makes plasma and memory cells - Plasma cells produce antibodies that attach to the antigens - Eater cells easily recognize these marked antigens and breaks it down - Memory cells stay around (B cells) Function of these antibodies: 1. Neutralize the toxins of antigens entering cells 2. Opsonization: attach antibodies to make pathogens easily identifiable 3. Agglutinate/clumping of pathogens 4. Complement activation: encourage other components to attach the pathogen, like lysosome
Describe the secondary immune response. What characteristic of viruses might explain why they sometimes do not cause a secondary immune response?
If the virus doesn't change and you get infected and make antibodies against it. There are memory cells that stick around for the second time they infect, but viruses mutate so rapidly so the memory cell antibodies wouldn't work on that virus anymore. Secondary Immune Response: - Antigens of viruses or bacteria or unfamiliar surface molecules (pathogens) are recognized in primary immune response. Antibodies are produced by the immune system as a result - They attach to the antigens and help to neutralize, opsonize, agglutinate, and complement activation, destroying the pathogen - Memory cells from a first exposure, either to the pathogen itself, or through vaccination, stay around - If the pathogen enters the body again, the memory cells help activate the immune system much faster, creating less, if any, symptoms. The person is said to be immune. - The antibody response is much bigger during secondary and much more rapid. Memory cells don't survive forever for some diseases Viruses no secondary immune response: - They need a host cell to carry out functions of life - Antibodies don't have an effect on viruses because they function on the processes of prokaryotic cells, like cell walls and membrane, protein synthesis, RNA/DNA - Viruses use host cells to "live" and therefore are considered a eukaryotic infection. So, antibodies can't be built up against them without harming the host's cells themselves - They are protected by host cell structure. They have no cell wall or membrane to attack
What effect does HIV have on the immune system?
It lowers the number of leukocytes in your immune system and reduces the amount of antibodies your body can produce. It inserts its RNA into T cells and kills them by blowing them up when there's too much virus in the one cell. This causes it to spread - It is a virus that gradually attacks our body's immune system. People infected have to fight harder to fight off infections and diseases - It can lead to AIDS, which is when the immune system is too weak to fight off infections. Leads to death. Happens when CD4+ cells drop below a critical level - It inserts its RNA into the host cells, which is incorporated into that cell's DNA. This causes an attack on T-helper cells by binding to a protein on its surface - It inserts the RNA into the macrophage genome where transcription ensues, created more viral RNA. Fewer antibodies can be produced, and the immune system weakens
Explain Florey and Chain's experiment with penicillin and what conclusions can be drawn from the results.
Penicillin may play a role in the recovery. They infected mice with a lethal dose of the bacteria. Some of them they give penicillin to and others they leave untreated. The ones with penicillin survived, and the ones without didn't. You can conclude that penicillin may play a role in recovery from the bacteria, but you can't say for a fact. - Tested chemical substances to control bacterial infections - They grew the fungus Penicillium in liquid culture, causing them to secrete penicillin. - It killed bacteria in agar plates. They tested it on mice and the ones injected with penicillin and exposed to bacteria lived. - They went straight to human testing after this, and burst an artery of a child. - Penicillin was then produced and tested more before commonly being used - Was not ethical and didn't follow modern testing procedures to consider side-effects, small dosage - Conclusion: you can find antibodies/pathogens/treatments in other organisms and use it in humans as protection. The fungi it is found in inhibits the growth of their bacterial competitors.
What is a pathogen?
Something that causes disease - Microbes/organisms that cause disease *bacteria like E coli *Protozoa like malaria parasite *Virus like influenza *Fungi like athletes foot - Transmitted through inhaled droplets, direct contact, bodily fluids, animal vectors, blood contact, ingestion
How does the concentration of antibodies differ from the first time one is exposed to an infectious disease and the 2nd exposure?
The first time that the pathogen enters, you'll produce a little amount, the second time it spikes right away. - During primary immune response, the build up of antibodies is not very strong and takes more time, whereas during the second exposure, there is a much bigger concentration of antibodies that are stronger and more rapid in response due to memory B cells being left behind that quickly recognize pathogens - In between a primary and secondary response, the amount of antibodies decreases due to no pathogen being present, but they are quickly gained again with the memory cells left behind
Which part of the immune system directly causes the symptoms of allergies?
The histamines set all of your allergy symptoms into motion. The amount and what they trigger are different from person to person. They are a non-specific form of immunity - Histamine: small organic molecules produced by basophil and mast cell leukocytes *Mast cells in connective tissues that release histamine in infected area *Basophils in the blood - Histamines increase the permeability of the capillaries to white blood cells and some proteins (like antibodies). This allows the immune system to engage the pathogen early at the site of infection - Fluid is lost from capillaries into surrounding tissues and causes inflammation, itching, sneezing, watery eyes - Allergies are hypersensitive reaction of the immune system to something in the environment that cause no problem for most people
Describe the steps involved in blood clotting.
The platelets and cell damage (from a wounded area) causes clotting factors (signal) to be released. These factors cause prothrombin to change to thrombin. Thrombin triggers fibrinogen that is in the blood soluble, to convert to fibrin, which is fibrous and insoluble. This forms a mesh in the wounded area that traps everything that floats by, like blood cells. It is exposed to air and dries to make a scab. - Clotting, or agglutination, happens when the wrong blood type with different antigens enters a person's body. This happens because antibodies attach to each other, causing pathogens to clump Wounds like cuts in the skin are an opening pathogens can enter the body - Platelets release clotting factors in response - Clotting factors cause a series of reactions where in the end, fibrin fibers form a mesh around the wound site, capturing blood cells and platelets to form a clot. It dries in a scab and shields the healing tissues. They prevent blood loss and entering of pathogens Steps: 1. Platelet/cell damage 2. Platelets aggregate at the site, forming a temporary plug 2. Clotting factors released 3. Thrombin protein turns soluble fibrinogen to insoluble fibrin 4. Protein captures erythrocytes by making a mesh 5. Clot forms 6. A gel is made at first, which turns into a hard scab - This can be dangerous during atherosclerosis, a disease where the artery wall becomes damaged, plaque forms and restricts blood flow. If this ruptures, blood clotting is triggered.
Why don't antibiotics work on viruses?
They don't have the same metabolism that the bacteria cells have. Don't have a cell wall, don't have the same metabolic processes that bacteria. The antibiotics are made to key in on prokaryotic systems so it doesn't work on our bodies for eukaryotic cells. So when the viruses enter our cells they can hide. - They need a host cell to carry out functions of life - Antibodies don't have an effect on viruses because they function on the processes of prokaryotic cells, like cell walls and membrane, protein synthesis, RNA/DNA - Viruses use host cells to "live" and therefore are considered a eukaryotic infection. So, antibodies can't be built up against them without harming the host's cells themselves - They are protected by host cell structure. They have no cell wall or membrane to attack - Antibiotics are designed to attack the structure or metabolic pathways of bacteria and fungi, not eukaryotic. Viruses have a very different shape - just protein capsid and genetic material - They only block bacterial DNA replication, transcription, translation, ribosome function, and cell wall formation
What causes a person to be immune to a disease after they have been vaccinated?
Two types of vaccination: 1. Active artificial Immunity: injected with pathogens to make you produce your own antibodies 2. Passive artificial Immunity: injected with antibodies of another organism Vaccination: - Contains antigens that trigger immunity but do not cause disease - Exposes them to antigens, creating a primary immune response. Memory cells are created and left behind so that if they are infected by the pathogen, they will have a quicker secondary response that is more rapid as the memory cells produce antibodies in response to the antigen How they have antigens: - Weakened or inactivated viruses - Weakened toxins - subunits (like part of a pathogen or just the antigen) Steps: 1. Exposed to vaccine 2. It triggers immunity by initiating primary immune response, then produces memory cells that can make antibodies in response to the antigen 3. When exposed to actual pathogen, the memory cell triggers secondary immune response that is faster/stronger 4. Little symptoms experienced
Explain how monoclonal antibodies are produced. What is the role of the hybridoma cells?
You use some sort of lab rat and stimulate their immune response by giving them the antigen. They start producing antibodies with B cells. You look for the B cell specific to that antigen and fuse it with a tumor cell. Now this is called a hybridoma cell, because it has the properties of both cells. It divides over and over again and you now have a lot of clones that make the right antibodies Monoclonal means they only respond to one antigen - Pathogens are injected into different animals, like mice, causing an immune response - The B cells produced in the animal are harvested from the spleen - They fuse the B plasma cell with a myeloma (tumor) cell, making hybridoma cells - They are screened to see which ones produce useful antibodies - These cells divide rapidly and therefore make a large number of clones. - These produce antibodies which are then collected to be used in humans for diagnostic tests and treatment Role: produces large quantities of genetically identical cells that produce the single specific antibody. Used for tests for malaria, HIV, pregnancy tests, or creating antibodies for rabies victims
