Chapter 27.9, Problem 26P

(a) Label all the O atoms that are part of a glycoside in rebaudioside A. Rebaudioside A, marketed under the trade name Truvia, is a sweet glycoside obtained from the stevia plant, which has been used for centuries in Paraguay to sweeten foods. (b) The alcohol or phenol formed from the hydrolysis of a glycoside is called an aglycon. What aglycon and monosaccharides are formed by the hydrolysis of rebaudioside A?

(g) Identify a simple lipid the list of compounds shown. ____________(h) Identify a complex lipid from the list of compounds shown. ____________(i) Identify a zwitterion from the list of compounds shown. ____________(j) Identify a lipid that is a constituent of cell membranes. ____________ write n/a if none

(i) Acetylation of glucose with acetic anhydride gives glucosepentaacetate. Write the structure of the pentaacetate.(ii) Explain why glucose pentaacetate does not react with hydroxylamine?

A) Explain the differences between the following: (a) Aldoses and ketoses (b) Reducing sugars and non-reducing sugars. B) Discuss the significance of anomeric carbon in carbohydrates. C) Explain the differences between globular and fibrous proteins. D) Explain the changes in the secondary and tertiary structure of proteins for the following: (a) Milk is heated at 60°C to make yogurt. (b) Prior to giving an injection, the skin is wiped with an alcohol swab.

h) Specify the absolute (R/S) configuration of the amino group in structure IV. (i) If the substituents in structures I, IV and V were identical (all OH or all NH2), which structure would result in a meso compound?  (j) If each hydroxy group for structures I, II and VI were replaced with another amino group, which compound would be made optically inactive?

Explain the meaning of the following: (a) Esterification (b) Saponification (c) Enantiomers

Draw both enantiomers of each amino acid and label them as R or S: (a) phenylalanine; (b) methionine.

Draw the structure of: (a) a polysaccharide formed by joining D-mannose units in 1->4-ß-glycosidic linkages; (b) a polysaccharide formed by joining D-glucose units in 1->6-a-glycosidic linkages. The polysaccharide in (b) is dextran, a component of dental plaque.

Consider the structure of raffinose, a trisaccharide found in sugar beets and a number of higher plants. HO CH,OH Но- OH OCH, Но Но OH НОСН Но CH,OH ÓH raffinose (a) Classify raffinose as a reducing or nonreducing sugar, and tell how you know. (b) Identify the glycoside linkages in raffinose, and clas- sify each as either a or B. (c) Name the monosaccharides formed when raffinose is hydrolyzed in aqueous acid. (d) What products are formed when raffinose is treated with dimethyl sulfate in NaOH, and then with aqueous acid and heat?