Carbohydrate Classification Flashcards
Sugars that are mirror images of each other are called what?
Enantiomers
What is a chiral (or stereogenic) carbon?
A carbon that has four different groups attached to it.
What is the difference between an aldose and ketose?
Aldose: contains one aldehyde group (C1)
Ketose: contains one ketone group (C2)
All monosaccharides are assigned the D or L configuration based on their relationship to glyceraldehyde. What does the symbol D or L designate on a carbohydrate?
Last chiral carbon furthest away from the aldehyde or ketone group.
(D and L are enantiomers!)
If the hydroxyl group (OH) on the last chiral carbon points to the right, is the absolute configuration D or L?
D
(D points to the right.)
For a Fischer projection, what are horizontal lines designated by? Vertical lines?
Horizontal lines = wedges (out of the page)
Vertical lines = dashes (into the page)
If the hydroxyl group (OH) on the last chiral carbon points to the left, is the absolute configuration D or L?
L
(L points to the left.)
What are isomers?
Molecules with identical molecular formulas but differ in the rearrangement of atoms.
What are diastereomers?
Two molecules with identical molecular formulas, different arrangement of atoms but are NOT enantiomers (mirror images).
What are epimers?
Two molecules that differ in configuration at ONLY one chiral carbon.
Which molecule is the aldose form of D-fructose?
D-glucose
D-glucose has the exact same molecular formula as D-fructose, but has an aldehyde functional group at one end.
For an aldose, which carbon of the carbohydrate will have the aldehyde group?
Carbon number one (C-1)
What are four of the most common monosaccharides?
- D-fructose
- D-glucose
- D-galactose
- D-mannose
For a ketose, which carbon of the carbohydrate will have the ketone group?
Carbon number two (C-2)
Which molecule is the ketose form of D-glucose?
D-fructose
D-fructose has the exact same molecular formula as D-glucose, but has a ketone functional group at one end.
