Discussion Board #1 PDF

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Regarding carbohydrates, which of the following statements is false? A. maltose and sucrose are disaccharides B. the difference between an aldose sugar and a ketose sugar is the number of carbons C. cellulose and amylose are polysaccharides D. glucose and ribose are monosaccharides E. in all monosaccharides, the ratio of carbon:hydrogen:oxygen is 1:2:1 Most of the chemicals that make up living things have a carbon backbone. The four categories that macromolecules can fall under include: carbohydrates, lipids, proteins and nucleic acids. Carbohydrates or sugars in particular are made up of carbonyl groups and hydroxyl groups. Carbohydrates can exist as simple sugars, monosaccharides or complex sugars, polysaccharides. Polymers of sugars are made from monosaccharides through dehydration synthesis. In the process, carbon atoms of monosaccharides link together by forming covalent bonds with an oxygen and releasing a water molecule. Carbohydrates function as a source of energy and as building blocks (Campbell, pg 66-70). Choice A is incorrect. A disaccharide is formed when two simple sugars go through dehydration synthesis. When two monosaccharides join together, they produce a disaccharide. Names of sugars usually end in “ose”. Glucose is a hexose and a common monosaccharide. Maltose is a product of two glucose molecules connecting by a glycosidic linkage. Fructose also a hexose and a monosaccharide. Sucrose is a product of a glucose and fructose linking together through dehydration synthesis (Campbell, pg 69). Choice A’s statement is true since both maltose and sucrose are disaccharides. Therefore it is not the right answer as we are looking for a false statement. Choice B is correct. The difference between an aldose and a ketose is the positioning of the carbonyl, not the number of carbons. Aldose is an aldehyde sugar and it’s carbonyl group is on a terminal carbon. Ketose is a ketone sugar and it’s carbonyl group is a central carbon (Erster, Lecture 4). Although carbohydrates can be classified by the number of carbons, the difference between an aldose sugar and ketose sugar is not the number of carbons. Thus this statement is false and choice B is the correct answer. Choice C is incorrect. When glucose forms a ring, the hydroxyl group attaches to the number 1 carbon above (beta) or below (alpha) the plane of the ring. Cellulose is a polymer of beta glucose. In cellulose, every other monomer is upside down in the polymer. Amylose is also a polymer of glucose. It is a simple starch and it is made up of alpha glucoses (Campbell, pg 69-70). As cellulose and amylose are indeed polymers, choice C cannot be the answer. Choice D is incorrect. Glucose is a monosaccharide. If the hexose is broken down, it will not remain a sugar. Ribose is another monosaccharide. Ribose has five carbons and is a pentose. Ribose and glucose can both join with other monomers to make polysaccharides (Campbell, pg 68). They are small molecules that serve as building blocks. Since it is true that glucose and ribose are monosaccharides, choice D is not the right answer.

Choice E is incorrect. All monosaccharides must have an empirical formula of CH2O (Campbell, pg 68). Empirical formulas give the ratio of the elements in the compound. Since the empirical formula is CH2O, the ratio of carbon to hydrogen to oxygen is 1 to 2 to 1. Thus choice E has a correct statement and thus cannot be the answer. Studying carbohydrates is very important. In a experiment from 2017, the antitumor properties of a polysaccharide from a marine alga Gracilariopsis lemaneiformis ( PGL) were studied. First the PGL was purified and then its properties were analyzed. The scientists treated different cancer lines with different concentrations of PGL for different periods of time. They found that when the concentration of PGL is more than 30 μg/mL, the PGL inhibits growth of cancer cell lines MKN28,  A549, and B16. Their  data proves that the polysaccharide of PGL hinders rapid growth of cells by promoting apoptosis or the death of cells. This indicates that the polysaccharide of PGL could be used to fight cancer in the future (Kang). I agree with Rifat Kabir’s answer. However, his application discusses the dietary impacts of complex carbohydrates. Carbohydrates are essential macromolecules, but they can have a negative effects, especially for those who are sensitive to the taste of carbohydrates. Excessive intake of carbohydrates can lead to weight gain, type 2 diabetes and heart disease (Gillaspy). According to the study Rifat wrote about, those who have high sensitivity intake more starch and have higher waist circumferences. They are thus more prone to developing type 2 diabetes or heart disease.

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Works Cited  enth Edition (Chapter 5). Pearson Taylor, Martha R., et al. Campbell Biology. T Education, Inc., 2013. Professor Erster’s Lecture 4 (January 29, 2018) Kang, Yani, et al. “Characterization and Potential Antitumor Activity of Polysaccharide from Gracilariopsis Lemaneiformis.” NCBI, PMC, 29 Mar. 2017, www.ncbi.nlm.nih.gov/pmc/articles/PMC5408246/. Gillaspy, Rebecca. “Health Effects of the Excessive Consumption of Carbohydrates.”Study.com, Study.com, 2018, study.com/academy/lesson/health-effects-of-the-excessive-consumption-of-carbohydrates .html....