Exam 25: Biomolecules: Carbohydrates

Exhibit 25-3 Refer to the monosaccharides below to answer each of the following question(s): Classify each sugar by type;for example,glucose is an aldohexose. -Refer to Exhibit 25-3.Erythrulose is _____.

Exhibit 25-12 Below is the structure of the antigenic determinant for the blood group B.Use this structure to answer the following question(s). -Refer to Exhibit 25-12.One of the monosaccharides is an unusual deoxy sugar called L-fucose.CIRCLE the L-fucose moiety.

Draw a Fischer projection of (2R,3S)-dibromobutane.

Exhibit 25-9 Choose a structure from the list provided below that best fits each of the following descriptions.Place the letter of the structure in the blank to the left of the description.There is only one correct answer for each question. -_____ a non-reducing disaccharide

Exhibit 25-4 From the sugars below,choose the one that best fits each description below.Place the letter of the sugar in the blank to the left of the description.There is only one correct answer for each question. -_____ a sugar with three chirality centers.

Exhibit 25-4 From the sugars below,choose the one that best fits each description below.Place the letter of the sugar in the blank to the left of the description.There is only one correct answer for each question. -Refer to Exhibit 25-4.Draw both chair conformations of the α-anomer of rhamnose in its pyranose form.Circle the more stable conformation.

Exhibit 25-4 From the sugars below,choose the one that best fits each description below.Place the letter of the sugar in the blank to the left of the description.There is only one correct answer for each question. -Refer to Exhibit 25-4.Name sorbose systematically.

Fructose reduces Tollens' reagent even though it contains no aldehyde group.This occurs because fructose is readily isomerized to an aldose in basic solution.Write the complete stepwise mechanism for the base-catalyzed isomerization of fructose to an aldohexose.Show all intermediate structures and all electron flow with arrows.

Compound U is an aldotetrose that can be oxidized to an optically active aldaric acid,compound V.Upon Wohl degradation,compound U is converted into D-glyceraldehyde.Upon Kiliani-Fischer chain extension,compound U is converted into compounds W and X.Compound W can be oxidized to an optically inactive aldaric acid,compound Y,but compound X is oxidized to an optically active aldaric acid Z.What are the structures of compounds U-Z?

Exhibit 25-2 Label each pair of stereoisomers below as: -_____

Exhibit 25-11 Consider the reaction below to answer the following question(s). -Refer to Exhibit 25-11.Place a triangle around the anomeric carbon in compound Q.

Melibiose is a reducing disaccharide that forms D-glucose and D-galactose on hydrolysis.Reaction of melibiose with iodomethane and silver oxide yields an octamethyl derivative,which can be hydrolyzed with aqueous acid to give one equivalent of 2,3,4,6-tetra-O-methyl-D-galactopyranose and one equivalent of 2,3,4,-tri-O-methyl-D-glucopyranose.If melibiose contains an α-glycosidic bond,what is its structure? ​

Exhibit 25-5 Refer to the equilibrium below to answer the following question(s). -Refer to Exhibit 25-5.Which enantiomer of ribose is drawn,D or L?

Exhibit 25-9 Choose a structure from the list provided below that best fits each of the following descriptions.Place the letter of the structure in the blank to the left of the description.There is only one correct answer for each question. -_____ a reducing monosaccharide

Exhibit 25-8 Draw structures for the products you would expect to obtain from reaction of β-D-galactopyranose with each of the following reagents.Be sure to include all relevant stereochemistry. β-D-galactopyranose -warm dilute HNO₃

Exhibit 25-8 Draw structures for the products you would expect to obtain from reaction of β-D-galactopyranose with each of the following reagents.Be sure to include all relevant stereochemistry. β-D-galactopyranose -CH₃I,Ag₂O

The Fischer projection for D-iodose corresponds to which pyranose below?

Exhibit 25-4 From the sugars below,choose the one that best fits each description below.Place the letter of the sugar in the blank to the left of the description.There is only one correct answer for each question. -Refer to Exhibit 25-4.Provide the complete name for the α-anomer of rhamnose in its pyranose form.

Exhibit 25-4 From the sugars below,choose the one that best fits each description below.Place the letter of the sugar in the blank to the left of the description.There is only one correct answer for each question. -Refer to Exhibit 25-4.Assign R or S configuration to each chirality center in sorbose.

Exhibit 25-8 Draw structures for the products you would expect to obtain from reaction of β-D-galactopyranose with each of the following reagents.Be sure to include all relevant stereochemistry. β-D-galactopyranose -NaOCH₃