Before a cell can reproduce, it must first replicate, or make a copy of, its DNA. Where DNA replication occurs depends upon whether the cells is a prokaryote or a eukaryote (see the RNA sidebar on the previous page for more about the types of cells). DNA replication occurs in the cytoplasm of prokaryotes and in the nucleus of eukaryotes.
Esophagogastroduodenoscopy (EGD) is a diagnostic procedure that allows the physician to diagnose and treat problems in the upper gastrointestinal (UGI) tract. The doctor uses a long, flexible, lighted tube called an endoscope. The endoscope is guided through the patient's mouth and throat, then through the esophagus, stomach, and duodenum (first part of the small intestine). The doctor can examine the inside of these organs and detect abnormalities.
An EGD may be performed on an outpatient basis or as part of your stay in a hospital. Procedures may vary, depending on your condition and your doctorâs practices. Generally, an EGD follows this process: You will be asked to remove any clothing, jewelry, or other objects that may interfere with the procedure.