Biochem Ch 10

Linking together one glucose, one mannose, and one galactose molecule can form how many different trisaccharides?

12,288

Which statements about reducing sugars are true? A disaccharide with its anomeric carbons joined by the glycosidic linkage cannot be a reducing sugar. Reducing sugars contain ketone groups instead of aldehyde groups. D‑Glucose (an aldose) is a reducing sugar. A reducing sugar will not react with the Cu2+Cu2+ in Benedict's reagent. The oxidation of a reducing sugar forms a carboxylic acid sugar.

A disaccharide with its anomeric carbons joined by the glycosidic linkage cannot be a reducing sugar. D‑Glucose (an aldose) is a reducing sugar. The oxidation of a reducing sugar forms a carboxylic acid sugar.

Acarbose and miglitol are competitive inhibitors of 𝛼-glucosidase. Identify the statement that describes how acarbose and miglitol decrease glucose absorption after a meal. Acarbose and miglitol bind to a regulatory site on 𝛼-glucosidase and inhibit the digestion of oligosaccharides in the small intestine. Acarbose and miglitol bind to the 𝛼-glucosidase active site and prevent the enzyme from binding to oligosaccharides in the small intestine and breaking them down to glucose. Acarbose and miglitol bind to a regulatory site on 𝛼-glucosidase and change the conformation of the enzyme to the inactive T state. Acarbose and miglitol bind to the 𝛼-glucosidase active site and prevent the enzyme from releasing the glucose formed from oligosaccharide breakdown in the small intestine.

Acarbose and miglitol bind to the 𝛼-glucosidase active site and prevent the enzyme from binding to oligosaccharides in the small intestine and breaking them down to glucose.

Which methods could be used to hydrolyze sucrose to invert sugar nonenzymatically in your kitchen at home? Add cream of tartar solution (pH≈4)(pH≈4) to the solution in a warm water bath. Add baking soda solution (pH≈9)(pH≈9) to the solution in a water bath. Add water to the solution and cool in an ice bath. Boil the sucrose solution in water.

Add cream of tartar solution (pH≈4)(pH≈4) to the solution in a warm water bath. Boil the sucrose solution in water.

The trisaccharide raffinose is a minor constituent of sugar beets and is composed of ___. Treatment of raffinose with β‑galactosidase produces ___. Raffinose is a ___ sugar.

D-galactose, D-glucose, D-fructose D-galactose and sucrose nonreducing

Epimers are monosaccharide diastereoisomers that have a single asymmetric carbon. Anomers are diastereoisomers in which the hemiacetal carbon of a cyclic monosaccharide is asymmetric. Determine whether each pair of monosaccharides consists of epimers, anomers, or an aldose‑ketose pair. D-glyceraldehyde and dihydroxyacetone alpha D-glucose and beta D-glucose D-glucose and D-fructose D-glucose and D-mannose D-ribose and D-ribulose D-galactose and D-glucose

Epimers: D-glucose and D-mannose D-galactose and D-glucose Anomers: alpha D-glucose and beta D-glucose Aldose-Ketose Pair: D-glyceraldehyde and dihydroxyacetone D-glucose and D-fructose D-ribose and D-ribulose

___ are the proteins involved in recognition of specific oligosaccharide structures.

Lectins

Determine whether each phrase describes starch, glycogen, or cellulose. major storage form of carbohydrates in plants major storage form of glucose in plants not digestible by humans made up of two glucose polysaccharides, amylose and amylopectin

Starch: major storage form of glucose in plants made up of two glucose polysaccharides, amylose and amylopectin Glycogen: major storage form of carbohydrates in plants Cellulose: not digestible by humans

Cellulose could provide an abundant and cheap form of glucose for humans. Why is cellulose not a source of nutrients for humans? Vertebrate enzymes hydrolyze (α 1-4) glucose linkages, but not glucose in the β configuration. Humans, and most vertebrates, lack the enzyme cellulase. Cellulose is a structural carbohydrate, and therefore is not useful as an energy source. Humans cannot absorb the hydrolyzed form of cellulose. Human gut bacteria break down cellulose in the large intestine, after nutrient absorption occurs.

Vertebrate enzymes hydrolyze (α 1-4) glucose linkages, but not glucose in the β configuration. Humans, and most vertebrates, lack the enzyme cellulase.

Then, UDP‑galactose is combined with another glucose unit to form a disaccharide. Identify the disaccharide.

lactose