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Pharmacy is the health profession that links the health sciences with the chemical sciences and it is charged with ensuring the safe and effective use of pharmaceutical drugs. The word derives from the Greek: (pharmakon), meaning "drug" or "medicine". The scope of pharmacy practice includes more traditional roles such as compounding and dispensing medications, and it also includes more modern services related to health care, including clinical services, reviewing medications for safety and efficacy, and providing drug information. Pharmacists, therefore, are the experts on drug therapy and are the primary health professionals who optimize medication use to provide patients with positive health outcomes. An establishment in which pharmacy (in the first sense) is practiced is called a pharmacy, chemist's or drug store. In the United States and Canada, drug stores commonly sell not only medicines, but also miscellaneous items such as candy (sweets), cosmetics, and magazines, as well as light refreshments or groceries.

Thursday, May 3, 2012

Synthesis of DNA

  • Replication of the genome requires DNA synthesis.
  • During replication, each of the two parental strands of DNA serves as a template for the synthesis of a complementary strand.
  • The site at which replication is occurring is called the replication fork.
  • Helicases and topoisomerases are required to unwind the DNA helix of the parental strands.
  • DNA polymerase is the major enzyme involved in replication.
  • DNA polymerase copies each parental template strand in the 3' to 5' direction, producing new strands in a 5' to 3' direction.
  • The precursors for replication are deoxyribonucleotide triphosphates.
  • As DNA synthesis proceeds in the 5' to 3' direction, one parental strand is synthesized continuously, whereas the other exhibits discontinuous synthesis, creating small fragments which are subsequently joined, because DNA polymerase must synthesize DNA in the 5' to 3' direction.
  • DNA polymerase requires a free 3' hydroxyl group of a nucleotide primer in order to replicate DNA. The primer is synthesized by the enzyme primase, which provides an RNA primer.
  • The enzyme telomerase synthesizes the replication of the ends of linear chromosomes (telomeres).
  • Errors during replication can lead to mutations, so error checking and repair systems function to maintain the integrity of the genome.
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