Mechanisms of Response essays

Mechanisms of Response essays The human body is built with its own immunity system. It provides defenses against foreign objects in the body and prevents disease. Specific diseases have a specific reaction- the immune system has a mechanism of response for each particular foreign substances. A foreign molecule that draws specific response lymphocytes is called an antigen; antigens are the molecules that are rejected by the body. Antigens are inclusive of molecules that belong to viruses, bacteria, fungi, protozoa, and parasitic worms. However, antigenic molecules can also be found on the surfaces of foreign materials such as pollen and transplanted tissue (as in the situation of a skin graft.) A skin graft is a patch of skin that is surgically removed from one part of the body and transplanted to another. It replaces tissue that has been destroyed or creates new tissue where none exists. One way that an antigen begins an immune response is by activating B cells to secrete proteins called antibodies. The term antigen is a contraction of anti-body-generator. Each antigen has a particular molecular shape and stimulates certain B cells to secrete antibodies that interact specifically with it. In fact, B and T lymphocytes even distinguish among antigens with molecular shape s that are only slightly different. So, in contrast to the nonspecific defenses, the immune system targets specific invaders. B cells and T cells can recognize specific antigens by their plasma membrane-bound antigen receptors. On B cells, these are actually transmembrane versions of antibody molecules and are often referred to as membrane antibodies. The antigen receptors on a T cell, called T cell receptors, are structurally related to membrane antibodies, and they recognize antigens just as specifically; contrary to antibodies, T cell receptors are never produced in a secreted form. Just one T or B cell can hold about 100,000 receptors for antigen, all with exactly the same specificity...

Definition and Examples of Infinitive Clauses

Definition and Examples of Infinitive Clauses In English grammar, an infinitive clause is a subordinate  clause whose verb is in the infinitive form. Also known as an infinitival clause or a to-infinitive clause The infinitive clause is called a clause because it may contain such clausal elements as a subject, object, complement, or modifier. Unlike most other subordinate clauses  in English, infinitive clauses are not introduced by a subordinating conjunction. Verbs that can be followed by infinitive clauses (as objects) include: agree, begin, decide, hope, intend, like, plan, and propose. Examples and Observations Im sorry but theres a handsome man in my spoon. Youll have to come back later.(Tom Tucker, The Kiss Seen Round the World. Family Guy, 2001)Jane was firm in her desire to live life on her own terms.Desperate to prove his innocence, Jamal tells the story of his life in the slums of Mumbai.If you want to make God laugh, tell him about your plans.(Yiddish proverb)We merely want​ to live in peace with all the world, to trade with them, to commune with them, to learn from their culture as they may learn from ours, so that the products of our toil may be used for our schools and our roads and our churches and not for guns and planes and tanks and ships of war.(President Dwight Eisenhower, quoted in Time magazine, 1955) Infinitive Clauses as Subjects and Objects A subordinate clause with an infinitive often acts as the subject or object of the main clause. In the following examples, the whole infinitive clause [in bold] is understood as the subject of is human, is decadent or was unnecessary. - To err is human.- To drink Martinis before noon is decadent.- For Mervyn to redirect Maggies mail was unnecessary. And in the following examples, the whole infinitive clause [again in bold] is understood as the direct object of hates, loves and expected. - Jim hates to wash his car.- Rosie loves to plan parties.- Phil expected Martha to stay at home all day. In case this is not obvious at first, you can test this by answering questions such as What does Jim hate? (answer: to wash his car), or What did Phil expect? (answer: Martha to stay at home all day). (James R. Hurford, Grammar: A Students Guide. Cambridge University Press, 1994) Perfect Infinitives To express time preceding that of the main verb, the infinitive takes a perfect form: to have past participle. (58) The parents were lucky to have found this specialist for their sick child. The perfect infinitive can be used with progressive aspect to emphasize duration. This construction consists of to have been V-ing. (59) He was too scared of the police to have been telling lies all the time. (Andrea DeCapua, Grammar for Teachers: A Guide to American English for Native and Non-Native Speakers. Springer, 2008) Passive Infinitives An infinitive that is derived from a passive finite verb clause will itself be passive: (20) a. I expect that all the calamari will be eaten before 7:00. (passive verb)(20) b. I expect all the calamari to be eaten before 7:00. (passive infinitive) You can verify that to be eaten is a passive infinitive in (20b) because it contains the passive marker [BE (-en)]: be eaten. Remember that eaten is a transitive verb; in its active form, it will have a subject (an indefinite pronoun like someone or they) and a direct object (all the calamari). (Thomas Klammer et al., Analyzing English Grammar, 5th ed. Pearson, 2007)