Los Pollos Hermanos_Week 4_Saccharides_Questions 21 and 22

Saccharides CELLULOSE & AMYLOSE BY: SAM TOWNE, SIMON YU, DERELL HAMPTON, DJJ JOHN, VINNY SHU, AND PETER YI #21- Cellulose is a polysaccharide which has ________. A) carbon-carbon bonds joining glucose units B) hemiacetal links joining glucose units C) only β-1,4-bonds between glucose units D) only α-1,4-links bonds glucose units E) both α-1,4-and α-1,6-bonds between glucose units The answer is not A, because... Carbon bonds are what constitute the structure of individual monosaccharides, while not being responsible for polysaccharide formation--such as cellulose. The answer is not B, because... The beta glucose, which is the monomer in cellulose, forms beta acetal linkages...not hemiacetal linkages. The answer is C, because Cellulose is a linear polysaccharide polymer with many glucose monosaccharide units. The acetal linkage is from beta glucose which makes it different from starch. Therefore, β -1,4-glycosidic bonds is the only bond for cellulose. The answer is not D, because... Cellulose naturally bond by the beta glucose to make the linkage in a linear chain. Therefore, a-1,4 cannot be happen with beta glucose linkage. The answer is not E, because... Cellulose is a polysaccharide of glucose units in unbranched chains with β-1,4-glycosidic bonds only. It does not have the option of α-1,4-glycosidic bonds, which is why it is insoluble in water and why humans cannot digest it. #22- Amylose is a form of starch which has ________. A) hemiacetal links joining glucose units B) only α-1,4-links bonds glucose units C) only β-1,4-bonds between glucose units D) both α-1,4-and β-1,4-bonds between glucose units E) carbon-carbon bonds joining glucose units The answer is not A, because... Amylose consists of 250 to 4000 α-D-glucose molecules connected by α-1,4-glycosidic bonds in a continuous chain. A hemiacetal compound is formed by formal addition of an alcohol to the carbonyl group, so these glucose molecules, in their current state, would not be considered hemiacetals. The answer is B, because... The reason the answer is α-1,4-glycosidic bonds in a continuous chain is because Amylose is made up of α(1→4) bound glucose molecules. The carbon atoms on glucose are numbered, starting at the aldehyde (C=O) carbon, so, in amylose, the 1-carbon on one glucose molecule is linked to the 4-carbon on the next glucose molecule (α(1→4) bonds) The answer is not C, because... The reason the answer is not only β-1,4-bonds between glucose units is because the molecule Cellulose is made of repeating beta 1,4-glycosidic bonds and these for indigestible foods where our body cant break down. These beta 1,4-glycosidic bonds, unlike the alpha 1,4 glycosidic bonds, force celullose to form long and sturdy straight chains that can interact with one another through hydrogen bonds to form fibers. The answer is not D, because... Answer choice D states that Amylose is a form of starch which has both alpha-1,4-and beta-1,4-bonds between glucose units. This statement is incorrect As you can see it in the picture, Amylose is a helical polymer that is only made of a-D-glucose units The answer is not E, because... The answer choice E states that amylose is a form of starch which has carbon-carbon bonds joining glucose units. E is not the correct answer. Although monosaccharides are rings made with carbon-carbon bonds, bond joining the glucose units is glycosidic bond resulting from condensation reaction. Sources: TIMBERLAKE, KAREN. CHEMISTRY: AN INTRODUCTION TO GENERAL, ORGANIC, AND BIOLOGICAL CHEMISTRY. 12TH ED. N.P.: PEARSON EDUCATION, 2015. PRINT.