The Difference Between Purines and Pyrimidines

Purines and pyrimidines are two types of aromatic heterocyclic organic compounds. In other words, they are ring structures (aromatic) that contain nitrogen as well as carbon in the rings (heterocyclic). Both purines and pyrimidines are similar to the chemical structure of the organic molecule pyridine (C5H5N). Pyridine, in turn, is related to benzene (C6H6), except one of the carbon atoms is replaced by a nitrogen atom. Purines and pyrimidines are important molecules in organic chemistry and biochemistry because they are the basis for other molecules (e.g., caffeine, theobromine, theophylline, thiamine) and because they are key components of the nucleic acids dexoyribonucleic acid (DNA) and ribonucleic acid (RNA). Pyrimidines A pyrimidine is an organic ring consisting of six atoms: 4 carbon atoms and 2 nitrogen atoms. The nitrogen atoms are placed in the 1 and 3 positions around the ring. Atoms or groups attached to this ring distinguish pyrimidines, which include cytosine, thymine, uracil, thiamine (vitamin B1), uric acid, and barbituates. Pyrimidines function in DNA and RNA, cell signaling, energy storage (as phosphates),  enzyme regulation, and to make protein and starch. Purines A purine contains a pyrimidine ring fused with an imidazole ring (a five-member ring with two non-adjacent nitrogen atoms). This two-ringed structure has nine atoms forming the ring: 5 carbon atoms and 4 nitrogen atoms. Different purines are distinguished by the atoms or functional groups attached to the rings. Purines are the most widely occurring heterocyclic molecules that contain nitrogen. They are abundant in meat, fish, beans, peas, and grains. Examples of purines include caffeine, xanthine, hypoxanthine, uric acid, theobromine, and the nitrogenous bases adenine and guanine. Purines serve much the same function as pyrimidines in organisms. They are part of DNA and RNA, cell signaling, energy storage, and enzyme regulation. The molecules are used to make starch and proteins. Bonding Between Purines and Pyrimidines While purines and pyrimidines include molecules that are active on their own (as in drugs and vitamins), they also form hydrogen bonds between each other to link the two strands of the DNA double helix and to form complementary molecules between DNA and RNA. In DNA, the purine adenine bonds to the pyrimidine thymine and the purine guanine bonds to the pyrimidine cytosine. In RNA, adenine bonds to uracil and guanine still bonds with cytosine. Approximately equal amounts of purines and pyrimidines are required to form either DNA or RNA. Its worth noting there are exceptions to the classic Watson-Crick base pairs. In both DNA and RNA, other configurations occur, most often involving methylated pyrimidines. These are called wobble pairings. Comparing and Contrasting Purines and Pyrimidines The purines and pyrimidines both consist of heterocyclic rings. Together, the two sets of compounds make up the nitrogenous bases. Yet, there are distinct differences between the molecules. Obviously, because purines consist of two rings rather than one, they have a higher molecular weight. The ring structure also affects the melting points and solubility  of the purified compounds. The human body synthesizes (anabolism) and breaks down (catabolism) the molecules differently. The end product of purine catabolism is uric acid, while the end products of pyrimidine catabolism are ammonia and carbon dioxide. The body does not make the two molecules in the same location, either. Purines are synthesized primarily in the liver, while a variety of tissues make pyrimidines. Here is a summary of the essential facts about purines and pyrimidines: Purine Pyrimidine Structure Double ring (one is a pyrimidine) Single ring Chemical Formula C5H4N4 C4H4N2 Nitrogenous Bases Adenine, guanine Cytosine, uracil, thymine Uses DNA, RNA, vitamins, drugs (e.g., barbituates), energy storage, protein and starch synthesis, cell signaling, enzyme regulation DNA, RNA, drugs (e.g., stimulants), energy storage, protein and starch synthesis, enzyme regulation, cell signaling Melting Point 214 C (417 F) 20 to 22 C (68 to 72 F) Molar Mass 120.115 gmol1 80.088 g mol1 Solubility (Water) 500 g/L Miscible Biosynthesis Liver Various tissues Catabolism Product Uric acid Ammonia and carbon dioxide Sources Carey, Francis A. (2008). Organic Chemistry (6th ed.). Mc Graw Hill. ISBN 0072828374.Guyton, Arthur C. (2006). Textbook of Medical Physiology. Philadelphia, PA: Elsevier. p. 37. ISBN 978-0-7216-0240-0.Joule, John A.; Mills, Keith, eds. (2010). Heterocyclic Chemistry (5th ed.). Oxford: Wiley. ISBN 978-1-405-13300-5.Nelson, David L. and Michael M Cox (2008). Lehninger Principles of Biochemistry (5th ed.). W.H. Freeman and Company. p. 272. ISBN 071677108X.Soukup, Garrett A. (2003). Nucleic Acids: General Properties. eLS. American Cancer Society. doi:10.1038/npg.els.0001335 ISBN 9780470015902.

John Beckett s The Glorious Revolution - 971 Words

John Beckett mentions that â€Å"the Glorious Revolution† has been considered a historical event related to the political issues. The main target of this historical event was to create a commercial freedom in Europe. After this revolution was done, trade relations in Europe went up, and the Bill of Rights was also created in 1689. Today, the Bill of Rights is shown and knowns that it was the first building stone for â€Å"the British constitution† because it limited the monarchic power. During the eighteenth century, the period of the Age of Enlightenment is considered â€Å"from 1713 to 1789† because Anthony Pagden states that Europe was like â€Å"a republic of states,† and it was like a union acting together and talking with one voice. The Age of Enlightenment was totally an act of improvement in trade, preventing and thwarting religion related wars, and monarchic rules. E. P. Thompson mentions that â€Å"the first industrial revolution† occu rred in England, and he mentions that there were not many modern things, but there was only a clock making industry. The discoveries of new places, peoples and things also brought the Agricultural revolution, financial improvement, and the Enlightenment and the Scientific progress, and all of these new findings and innovations triggered to form the Industrial Revolution in England. Hence, the Glorious Revolution, the Age of Enlightenment and the Industrial Revolution should be considered as the first historical roots of the European Union because these

Susan’s intervention plan Free Essays

Reply to Response #1 I agree with you. Susan’s intervention plan is a good one and might just work given the necessary support from everyone concerned. Carl is not a hopeless case. We will write a custom essay sample on Susan’s intervention plan or any similar topic only for you Order Now His having been diagnosed with a behavior disorder which was apparently caused by his parents’ divorce three months previously did not make him a basket case. Actually, what Carl needs is attention and love which he feels was denied him by his parents as a result of their separation. Susan should therefore convince Mrs. Taylor that totally giving up on Carl by taking him out of her class altogether would not help at all. On the contrary, it would aggravate the situation as it would only remind him of the betrayal he believes he suffered from his parents. My reading of the case is that Carl could be saved if only everybody – his parents, Mrs. Taylor, and Susan – are prepared to show him that they would not give up on him. Carl is only misbehaving because he wants attention. Totally denying him of such attention might push him towards the point of no return. Reply to Response #2 Yes, it is evident that what Nancy really wants is to have Carl out of her class. She is not interested in doing anything more for him and appears to have entirely lost her patience. However, patience is what Carl needs most. He has been showing disrespect not only to Nancy but to the other teachers as well because his behavior disorder was caused by what he believed was an act of betrayal on the part of his divorced parents. In other words, he is merely taking it out on them. If the teachers at Skyler K through 12 Comprehensive School are not patient with Carl, his behavior disorder might develop into something more damaging. Reply to Response #3 I agree that talking with Carl might help. Susan could arrange a one-on-one session with Carl after class and establish rapport, befriend him. It could be that an adult friend is what Carl really needs under the circumstances, having â€Å"lost his parents to divorce. † I also agree with you that Carl’s behavior could very well be a defensive posture on Carl’s part because apparently, he has started feeling â€Å"unsafe† after his parents separated. In other words, Carl is feeling inadequate and insecure and persecuting him – like taking him out of Nancy’s class altogether – might push him over the edge. How to cite Susan’s intervention plan, Papers

Anatomy and Physiology free essay sample

The vagina is a  thin-walled tube 8 to  10 cm  long. It lies between the bladder and rectumand extends from the cervix to the body exterior. Often called the birth canal, the vagina providesa passageway for the delivery of an  infant and for the menstrual flow to leave  the body. The cervix (from Latin neck) is the lower, narrow portion of the uterus where it joinswith the top end of the vagina. Approximately half its length is visible with appropriate medical equipment; the remainder liesabove the vagina beyond view. It is occasionally called cervix uteri, or neck of the uterus. During menstruation, the cervix stretches open slightly to allow the endometrium to beshed. This stretching is believed to be part of the cramping pain that many women experience. Evidence for this is given by the fact that some womens cramps subside or disappear after their  first vaginal birth because the cervical opening has widened. We will write a custom essay sample on Anatomy and Physiology or any similar topic specifically for you Do Not WasteYour Time HIRE WRITER Only 13.90 / page The portion projecting into the vagina is referred to as the portio vaginalis or ectocervix. On average, the ectocervix is three cm long and two and a half cm wide. It has a convex,elliptical surface and is divided into anterior and posterior lips. The ectocervixs opening is calledthe external os. The size and shape of the external os and the ectocervix varies widely with age,hormonal state, and whether the woman has had a vaginal birth. In women who have not had avaginal birth the external os appears as a small, circular opening. During childbirth, contractions of the uterus will dilate the cervix up to 10 cm in diameter  to allow the child to pass through. During orgasm, the cervix convulses and the external osdilates. The uterus is shaped like an upside-down pear, with a thick lining and muscular walls. Located near the floor of the pelvic cavity, it is hollow to allow a blastocyte, or fertilized egg, toimplant and grow. It also allows for the inner lining of the uterus to build up until a fertilized eggis implanted, or it is sloughed off during menses. The uterus contains some of the strongest muscles in the female body. These muscles areable to expand and contract to accommodate a growing fetus and then help push the baby outduring labor. These muscles also contract rhythmically during an orgasm in a wave like action. It20 is thought that this is to help  push or guide the sperm up  the uterus to the fallopian tubes wherefertilization may be possible. The uterus is only about three inches long and two inches wide, but during pregnancy itchanges rapidly and dramatically. The top rim of the uterus is called the fundus and is alandmark for many doctors to track the progress of a pregnancy. It is only after all alternative options have been considered that surgery isrecommended in these cases. This surgery is called hysterectomy. Hysterectomy is the removalof the uterus, and may include the removal of one or both of the ovaries. Once performed it isirreversible. After a hysterectomy, many women begin a form of alternate hormone therapy dueto the lack of ovaries and hormone production. The Fallopian tubes are paired, tubular, seromuscular organs whose course runs mediallyfrom the cornua of the uterus toward the ovary laterally. The tubes are situated in the upper  margins of the broad.