02.02 - Review of Carbohydrates Flashcards
In Haworth projections, why is the chair conformation more stable than the boat conformation?
a. There is less steric interference with C3, C4, and C5
b. C1 lacks an -OH group.
c. The boat form has two -OH groups at C3.
d. A and B
a. There is less steric interference with C3, C4, and C5
True or False: Monosaccharides cannot be broken down into simpler sugars.
False. This is only true for mild conditions, but in the presence of enzymes, monosaccharides can be broken down into simpler forms (e.g. in glycolysis, glucose is broken down to glyceraldehyde and dihydroxyacetone).
What disaccharide is formed after the synthesis of two glucose subunits?
Maltose
Sucrose is composed of which two sugars?
Glucose and fructose
Lactose is composed of which two monosaccharides?
Glucose and galactose
Which is true about glucose?
a. It is a ketose, with a C=O found at the non-terminal C2.
b. It is a ketose, with a C=O found at the terminal end.
c. It is an aldose, with a C=O found at the non-terminal C2.
d. It is an aldose, with a C=O found at the terminal end.
d. It is an aldose, with a C=O found at the terminal end.
Which of the following is not a ketose?
a. Galactose
b. Fructose
c. Dihydroxyacetone
c. Ribulose
a. Galactose (it is an aldose)
These are molecules with the same formula and same structure but are non-superimposable mirror images of one another.
a. Diastereomers
b. Epimers
c. Anomers
d. Enantiomers
d. Enantiomers
Beta-D-glucose is a/an ___________ of a-D-glucose.
a. Epimer
b. Diastereomer
c. Anomer
d. Enantiomer
c. Anomer
These are diastereomers that differ only in one chiral carbon.
Epimers
A certain hexose has 3 chiral centers. How many stereoisomers of the hexose exist?
8 (2^3)
Anomers are:
a. Configurational isomers
b. Conformational isomers
c. Epimers
d. Diastereomers
b. Conformational isomers
Which of the following is correctly paired?
a. D-fructose - furanose
b. D-Glucose - furanose
c. D-fructose - pyranose
d. B and C
a. D-fructose - furanose
Which of the following is true?
a. Glycosides (e.g. glucosamine) are sugars with an amino group substituted for a hydroxyl group.
b. Gluconolactone, which is derived from an oxidized glucose product called gluconic acid, reacts with the substance present in the glucometer.
c. Sugar alcohols are made by the oxidation of the carbonyl group.
d. Phosphorylated derivates (e.g. ribose) are made by esterifying a phosphate group to a carbonyl group in the sugar.
b. Gluconolactone, which is derived from an oxidized glucose product called gluconic acid, reacts with the substance present in the glucometer.
Which is not true about the formation of disaccharides?
a. It is an energy-requiring process.
b. It occurs with the removal of water.
c. Sucrose forms after the linkage of C2 of glucose and C1 of fructose.
d. Lactose are essentially glucose and galactose subunits connected by a 1,4 glycosidic bond.
c. Sucrose forms after the linkage of C2 of glucose and C1 of fructose. (In sucrose, the C1 of glucose and C2 of fructose are linked.)
