Proteins and Amino Acids Chapter 2

41) Children with kwashiorkor typically have a diet that is high in carbohydrates and extremely low in. A) calcium. B) fats. C) glucose. D) protein. Answer: D 42) Individuals 18 years of age and younger should consume ________ grams of protein for each kilogram of body weight. A) 0.80 B) 0.75 C) 0.85 D) 0.90 Answer: C 43) A gram of protein contains ________ calories. A) 5 B) 10 C) 4 D) 3 Answer: C 44) A person fighting a fever would be in ________ nitrogen balance. A) positive B) negative C) equal D) double-negative Answer: B 45) The nitrogen removed from an amino acid generates ammonia, which is converted to ________ and excreted in the urine. A) urea B) protein C) carbon D) sodium Answer: A 46) All excess calories are stored as A) protein. B) fat. C) collagen. D) plaque. Answer: B 47) The condition characterized by a severe deficiency of calories is known as A) kwashiorkor. B) marasmic kwashiorkor. C) edema. D) marasmus. Answer: D 48) The molecule that directs protein synthesis in cells is A) DNA. B) mRNA. C) tRNA. D) pepsin. Answer: A 49) An amino acid that can be synthesized in the body is considered to be A) complementary. B) essential. C) nonessential. D) conditional. Answer: C 50) A rare genetic disorder, phenylketonuria (PKU), is caused by the body's inability to properly degrade A) ketones. B) phenylalanine. C) lysine. D) valine. Answer: B 51) Once DNA leaves the nucleus, mRNA copies of it are made and brought to a ribosome. Answer: FALSE 52) Plant proteins may be less digestible, especially when eaten raw. Answer: TRUE 53) Hemoglobin acts as a transport protein that carries nitrogen to cells from the lungs. Answer: FALSE 54) Whole-wheat bread contains complete proteins. Answer: FALSE 55) Proteins within the body help to maintain fluid balance but not acid-base balance. Answer: FALSE 56) During periods of starvation, the carbon skeletons of amino acids are used for energy and for gluconeogenesis. Answer: TRUE 57) People with marasmus are starving. Answer: TRUE 58) Children with kwashiorkor have a difficult (if not impossible) time fighting infections. Answer: TRUE 59) A protein is considered a complete protein if it contains all eleven nonessential amino acids and some of the nine essential amino acids. Answer: FALSE 60) Numerous research studies have shown that bones lose calcium when a person's diet is too high in protein. Answer: TRUE 61) Vitamin A is found only in animal foods, but vegetarians can meet their needs by consuming its precursor, beta-carotene. Answer: TRUE 62) A typical healthy adult is normally in a state of positive nitrogen balance. Answer: FALSE 63) The absorption of zinc is inhibited by animal protein. Answer: FALSE 64) A high-protein diet has been linked to a lower risk of heart disease. Answer: FALSE 65) Consuming too much of any one amino acid in protein supplements can impede absorption of other amino acids in the intestinal tract. Answer: TRUE 66) Vegetarians can consume adequate protein only by eating a variety of vegetables and fish. Answer: FALSE 67) Some nonessential amino acids can become conditionally essential if the body cannot make them because of bouts of illness. Answer: TRUE 68) When amino acids are broken down, they lose their amine groups. Answer: TRUE Page Ref: 194 69) Isoflavones are weak estrogens that naturally occur in plants. Answer: TRUE 70) An RNA segment that codes for a specific protein is a gene. Answer: FALSE 71) The type of RNA that collects the amino acids needed to make a protein is called mRNA. Answer: FALSE 72) The type of RNA that copies information in a DNA molecule is called tRNA. Answer: FALSE 73) A ribosome builds a chain of amino acids in the proper sequence. Answer: TRUE 74) RNA contains the genetic information for the cell. Answer: FALSE 75) Proteins that bind to and neutralize pathogens in your body are called antibodies. Answer: TRUE 76) Enzymes are biological catalysts that slow down reactions. Answer: FALSE 77) The PDCAAS is a measure of protein quantity. Answer: FALSE 78) The composition of amino acids in a protein is called the amino acid profile. Answer: TRUE 79) Complemented proteins result from the combination of two incomplete proteins. Answer: TRUE 80) According to the NIH, approximately one in twelve African Americans and one in 100 Asians are carriers of the mutated gene that causes sickle-cell anemia. Answer: FALSE 81) Explain the difference between an incomplete protein and complete protein. Give an example of a food containing each of these types of protein. Answer: An incomplete protein is a protein that is low in one or more of the essential amino acids; beans contain incomplete protein. A complete protein is a protein that provides both all nine essential amino acids and some of the eleven nonessential amino acids; chicken contains complete protein. 82) Describe the basic structure of an amino acid. Answer: Each amino acid consists of a central carbon atom (C) surrounded by four other components: an acid group (COOH), an amine group (NH2), a hydrogen atom (H), and one of 20 unique side chains that determines the identity of the amino acid. 83) Discuss the advisability of regularly consuming protein bars. Answer: If they are being consumed because they are convenient and portable, a simple peanut butter sandwich is just as convenient and portable at a tenth of the cost. Protein bars also have more sugar and less fiber than the sandwich, and more saturated fat. All in all, there are healthier choices than protein bars. 84) What is the difference between an essential amino acid and a nonessential amino acid? Answer: Essential amino acids must be consumed in the diet because the body cannot make them. Some nonessential amino acids can be made from other amino acids by the liver. 85) Why might a vegetarian diet also be a lower-calorie diet than one that includes meat and dairy products? Answer: A vegetarian diet contains mostly fiber-rich whole grains and low-calorie, nutrientdense vegetables and fruits. These foods "fill you up before they fill you out," which means you are likely to eat fewer calories overall. 86) Under what circumstances are the body's proteins broken down to provide energy for the body? Is this a good thing to have happen? Answer: Proteins are broken down to provide energy for the body when caloric intake is inadequate. This is an undesirable situation; the body's energy needs are better met by consuming adequate amounts of calories from carbohydrates and fat, and using proteins to provide energy produces waste products that must be eliminated from the body. Proteins are best reserved for their many important roles other than providing energy. 87) Briefly describe protein synthesis in a cell. Include the following terms: nucleus, ribosome, DNA, mRNA, tRNA, amino acids, and cytoplasm. Answer: DNA in the nucleus stores the coded genetic information needed for making proteins. DNA can't leave the nucleus of the cell; instead, messenger RNA (mRNA) made in the nucleus takes a copy of the information to a ribosome in the cytoplasm. The ribosome moves along the mRNA, reading the code. Another type of RNA–transfer RNA (tRNA)–picks up an amino acid that is needed to build a specific protein and carries it to a ribosome. (There are 20 different tRNAs, one for each amino acid.) The ribosome then builds the protein by connecting the amino acids in the proper sequence as directed by the code in the mRNA. The ribosome continues to move down the mRNA strand until each of the appropriate amino acids has been added and the protein is complete. 88) Explain why severe edema is a common sign in kwashiorkor. Answer: Kwashiorkor is characterized by an inadequate and unbalanced diet that is high in carbohydrate-rich grains but severely deficient in protein. Protein plays an important role in maintaining fluid balance in the blood and around the cells. With protein deficiency, fluid accumulates in the spaces surrounding the cells, causing edema (swelling). 89) Describe at least four ways the body uses proteins. Answer: Proteins provide structural and mechanical support, maintain body tissues, build most enzymes and many hormones, help maintain fluid balance and acid-base balance, transport substances throughout the body, contribute to a healthy immune system, improve satiety and 90) What are the potential risks and benefits of a vegetarian diet? Answer: Benefits: A vegetarian diet is low in fat (especially saturated fat and cholesterol) and high in fiber-rich plant foods that contain beneficial phytochemicals. This type of diet has been shown to reduce the risk of heart disease, high blood pressure and stroke, type 2 diabetes, certain kinds of cancer, and obesity. Risks include under-consumption of protein, vitamin B12, iron, zinc, calcium, vitamin D, riboflavin, vitamin A, and omega-3 fatty acids.