Ch 25 Flashcards
monosaccharides usually have molecular formulas of
CnH2nOn OR just Cn(H2O)n
carbohydrates are … aldehydes or ketones or compounds that … polyhydroxylated aldehydes/ketones upon ..
polyhydroxylated; produce; hydrolysis
In a Fischer projection, the monosaccharide is drawn in the open-chain form and the carbonyl atom is placed at the … of the structure. Horizontal lines represent groups protecting … the plane of the paper, and vertical lines represent groups protecting … the plane of the paper
top; above; below
In a monosaccharide, the point of reference is the chiral center that is … from the carbonyl group. Because this is a C atom that is the next-to-the-last C atom in the chain (notice that the last C atom of the chain in a typical carb has two H atoms, so it is not a chiral center), it is referred to as the … C atom
farthest; penultimate
A monosaccharide that has the same configuration about its penultimate C as D-glyceraldehyde is classified as a(n) …-monosaccharide. In this case, the OH group is on the … side of the C atom the Fischer projection
D; right
A(n) ..-monosaccharide has a config about its penultimate C atom that is the same as the configuration of L-glyceraldehyde, with the OH group on the … in a Fischer projection;
L; left
Notice that the enantiomer of a given monosaccharide is not produced by simply changing the config of the penultimate C, but rather by reversing the
configuration of all the chiral centers
when a carb form a six-membered hemiacetal ring, it is called a …, and when a carb forms a five-membered hemiacetal ring, it is called a …
pyranose; furanose
In a Haworth projection, OH’s that are on the right in a Fischer projection are drawn as facing … and OHs that are on the left in a Fischer are drawn as facing …
down; up
The alpha anomer has the anomeric OH and the terminal CH2OH group on … sides of the ring in a Haworth projection
opposite
the beta anomer has the anomeric OH group on the … side of the ring as the CH2OH group in a Haworth projection
same
a glycoside is an … derived from a monosaccharide, and the bond from the anomeric C to the OR group is called the … bond
glycoside; glycosidic
the name of the glycosidke is composed of the name of the alkyl/aryl group bonded to the acetal O atom followed by the name of the monosaccharide in which the terminal -e has been replaced with
ide
glycosidic bonds can be made by reacting a saccharide with an .. in .., following the standard acetal formation mechanism
alcohol; acid
an alditol is a polyhydroxy compound formed by .. of the carbonyl group of a monosaccharide to a … group.
reduction; hydroxyl
an aldonic acid is a carboxylic acid formed by … of the aldehyde group of an aldose. oxidation of D-glucose, for example, gives D-gluconic acid
oxidation
reducing sugars are those sugars that are … by mild oxidizing agents to aldonic acids
oxidized
..-catalyzed oxidation of the primary hydroxyl group at C6 of a hexose yields a uronic acid
enzyme
periodic acid cleaves the C-C bond of a glycol in a reaction that proceeds through a … this rxn was once useful in carb structure determination
cyclic periodic ester
a disaccharide contains two … units joined by a … bond
monosaccharide; glycosidic
sucrose is a disaccharide containing … joined to … by an … glycosidic bond
D-glucose; D-fructose; alpha-1,2
lactose is a disaccharide consisting of … joined to … by a … glycosidic bond
D-galactose; D-glucose; beta-1,4
maltose is a disaccharide of two molecules of … joined by an … bond
D-glucose; alpha-1,4 glycosidic
