Porth’s Essentials of Pathophysiology 5th Edition Test Bank QUESTIONS AND ANSWERS WITH EXPLANTIONS

Porth’s Essentials of Pathophysiology 5th Edition Test Bank Chapter 1 Although the basic structure of the cell plasma membrane is formed by a lipid bilayer, most of the specific membrane functions are carried out by: A) Bound and transmembrane proteins B) Complex, long carbohydrate chains C) Surface antigens and hormone receptors D) A gating system of selective ion channels Ans: A Feedback: The functions of plasma membrane depend on the presence of proteins that are bound in the lipid bilayer and some that have the ability to pass freely into and out of the cell. Carbohydrate chains form a cell coat that surrounds the membrane and that contain surface antigens and surface hormone receptors. Some ion channels are gated and open only when the membrane potential changes significantly. 2. Which describes the function of the nucleus? A) It is basically the site of protein synthesis in the body. B) It contains the genetic code for the individual. C) It is the transformer of cellular energy. D) It initiates the process of aerobic metabolism. Ans: B Feedback: The nucleus contains DNA, which contains the genetic code that contains the information that controls cells. Ribosomes synthesize protein. Mitochondria transform organic compounds into cellular energy. Mitochondria require oxygen for aerobic metabolism, using hydrogen and carbon combined with oxygen molecules to form carbon dioxide and water as energy is released. 3. Which of the following aspects of the function of the nucleus is performed by ribosomal RNA (rRNA)? A) Copying and carrying DNA instructions for protein synthesis B) Carrying amino acids to the site of protein synthesis C) Providing the site where protein synthesis occurs D) Regulating and controlling protein synthesis Ans: C Feedback: There are three types of ribonucleic acid (messenger RNA, ribosomal RNA, and transfer RNA) that move to the cytoplasm and carry out the actual synthesis of proteins. Messenger RNA (mRNA) copies and carries the DNA instructions for protein synthesis to the cytoplasm; ribosomal RNA (rRNA) is the site of protein synthesis; and transfer RNA (tRNA) transports amino acids to the site of protein synthesis for incorporation into the protein being synthesized.