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Unformatted text preview: Biology 445/545 Biology of Toxins Study Questions 1. Grab your dictionary and look up the definition of "toxic". Is oxygen toxic? Is water? Are there any substances that aren't toxic? What determines whether something is toxic? Toxic- of, pertaining to, affected with, or caused by a toxin or poison. Acting as or having the effect of a poison; poisonous: a toxic drug. Everything is toxic; it just depends on the quantity. 2. Look up the definition of xenobiotic ? How is the word relevant to toxicology? Xenobiotic- a chemical or substance that is foreign to an organism or biological system. Toxins are foreign substances that get into your body and produce an effect. 3. Give a good definition of a toxin. Why do organisms produce toxins? Toxin- is any poison produced by an organism, characterized by antigenicity in certain animals and high molecular weight, and including the bacterial toxins that are the causative agents of tetanus, diphtheria, etc., and such plant and animal toxins as ricin and snake venom. Toxin- A poisonous substance, especially a protein, that is produced by living cells or organisms and is capable of causing disease when introduced into the body tissues but is often also capable of inducing neutralizing antibodies or antitoxins. Organisms produce toxins to protect themselves 4. What is a venom? Venom- the poisonous fluid that some animals, as certain snakes and spiders, secrete and introduce into the bodies of their victims by biting, stinging, etc. It is usually injected and is usually a mixture of individual toxins. Cell Biology Review ( you should be able to answer these from your cell biology background ) 5. What is an enzyme? Why are enzymes important to organisms? Enzyme- Any of numerous proteins produced in living cells that accelerate or catalyze the metabolic processes of an organism. Enzymes are usually very selective in the molecules that they act upon, called substrates , often reacting with only a single substrate. The substrate binds to the enzyme at a location called the active site just before the reaction catalyzed by the enzyme takes place. Enzymes can speed up chemical reactions by up to a million fold, but only function within a narrow temperature and pH range, outside of which they can lose their structure and become denatured. Enzymes are involved in such processes as the breaking down of the large protein, starch, and fat molecules in food into smaller molecules during digestion, the joining together of nucleotides into strands of DNA, and the addition of a phosphate group to ADP to form ATP. The names of enzymes usually end in the suffix -ase. They are important to organisms because they increase the rate of reactions but they dont alter the equilibrium constants. 6. Describe the basic model of an enzyme-catalyzed reaction. What is the active site? What is the significance of the lock-&-key hypothesis?...
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- Spring '08