![]() ![]() For example, the terms triose, tetrose, pentose, and hexose signify monosaccharides with, respectively, three, four, five, and six carbon atoms. Monosaccharides of specific sizes may be indicated by names composed of a stem denoting the number of carbon atoms and the suffix - ose. The naturally occurring monosaccharides contain three to seven carbon atoms per molecule. ![]() Distinguish between a D sugar and an L sugar.Classify monosaccharides as aldoses or ketoses and as trioses, tetroses, pentoses, or hexoses.All these so-called higher saccharides can be hydrolyzed back to their constituent monosaccharides. ![]() Chains with many monosaccharide units joined together are called polysaccharides. Disaccharide molecules have two monosaccharide units, trisaccharide molecules have three units, and so on. Prefixes are used to indicate the number of such units in the chains. Two or more monosaccharides can link together to form chains that contain from two to several hundred or thousand monosaccharide units. The simplest carbohydrates-those that cannot be hydrolyzed to produce even smaller carbohydrates-are called monosaccharides. We use carbohydrates not only for food (about 60%–65% by mass of the average diet) but also for clothing (cotton, linen, rayon), shelter (wood), fuel (wood), and paper (wood). Carbohydrates are also needed for the synthesis of nucleic acids and many proteins and lipids.Īnimals, including humans, cannot synthesize carbohydrates from carbon dioxide and water and are therefore dependent on the plant kingdom to provide these vital compounds. We can gather and eat the parts of a plant that store energy-seeds, roots, tubers, and fruits-and use some of that energy ourselves. Starch provides energy for later use, perhaps as nourishment for a plant’s seeds, while cellulose is the structural material of plants. (The 686 kcal come from solar energy.) Plants can use the glucose for energy or convert it to larger carbohydrates, such as starch or cellulose. Green plants are capable of synthesizing glucose (C 6H 12O 6) from carbon dioxide (CO 2) and water (H 2O) by using solar energy in the process known as photosynthesis:ĦCO 2 + 6H 2O + 686 kcal → C 6H 12O 6 + 6O 2 Which compounds would be classified as carbohydrates? Later we will study the other three major types of macromolecules found in living organisms: lipids, proteins, and nucleic acids. Glucose is one of the carbohydrates you will learn about in this chapter as we begin the study of biochemistry-the chemistry of molecules found in living organisms. Following a diagnosis of diabetes a person will need to monitor his or her blood glucose levels daily (or more often) using a glucose meter. Individuals with a value between 140 and 199 mg/dL are diagnosed with prediabetes, while those with a value of 200 mg/dL or above are diagnosed with diabetes. At the second measurement, the glucose plasma level should be no higher than 139 mg/dL. A first measurement is made after a fast of at least 8 h, followed by another measurement 2 h after the person drinks a flavored solution of 75 g of glucose dissolved in water. The characteristic symptoms of diabetes are weight loss, constant hunger, extreme thirst, and frequent urination (the kidneys excrete large amounts of water in an attempt to remove the excess sugar from the blood).Īn important diagnostic test for diabetes is the oral glucose tolerance test, which measures the level of glucose in blood plasma. People with diabetes are impaired in their ability to metabolize glucose, a sugar needed by the body for energy as a result, excessive quantities of glucose accumulate in the blood and the urine. Moreover, it was a contributing factor in over 200,000 deaths in which the cause was listed as something else, such as heart or kidney disease. In 2006, diabetes was the seventh leading cause of death, listed on 72,507 death certificates. In the United States, 17.9 million people have been diagnosed with diabetes, and experts estimate that at least another 5.7 million people have the disease but have not been diagnosed. ![]()
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