Mcat Biochemistry (Chapter 4)

organized by their number of carbon atoms and functional groups

glucose

fructose

galactose

trioses

tetroses

sugars with aldehydes (the CHO) as their most oxidized group

sugars with ketones (ROR) as their most oxidized group; can act as reducing sugars because they undergo tautomerization to undergo keto-enol shifts which forms an aldose

the D- and L- forms of glyceraldehyde

sugars with the highest-numbered chiral carbon with the -OH group on the right (in a Fischer projection)

sugars with the highest-numbered chiral carbon with the -OH group on the left (in a Fischer projection)

enantiomers

chiral molecules that are mirror images of each other; non-superimposable; have equal but opposite optical activities

nonsuperimposible configurations of molecules with similar connectivity; they differ at at least one, but not all, chiral carbons; these include epimers and anomers

subtype of diastereomers that differ at exactly one chiral carbon

subtype of epimers that differ at the anomeric carbon; this is in cyclic compounds

describes the ring formation of carbohydrates from their straight-chain forms; when rings form, the anomeric carbon can take on either an α- or β-conformation

the new chiral center formed in ring closure; it was the carbon containing the carbonyl in the straight-chain form

have the -OH on the anomeric carbon trans (pointing down) to the free -CH2OH group

have the -OH on the anomeric carbon cis (pointing up) to the free -CH2OH group

provide a good way to represent three-dimensional structure (in cyclic compounds)

cyclic compounds can undergo this process in which they shift from one anomeric form to another with the straight-chain form as an intermediate

single carbohydrate units, with glucose as the most commonly observed monomer; they can undergo three main reactions:

oxidation-reduction

esterification

glycoside formation

form after the aldehyde group on a reducing sugar reduces another compound, becoming oxidized in the process; an aldose which has been oxidized

aldoses that have been reduced

sugars that can be oxidized and are reducing agents

Tollen's or Benedict's reagents

sugars with an -H replacing an -OH group

the process of sugars reacting with carboxylic acids and their derivatives and forming esters

reaction in which a phosphate ester is formed by transferring a phosphate group from ATP onto a sugar

refers to the reaction between an alcohol and a hemiacetal or hemiketal group on a sugar to yield an alkoxy group (alkyl group singularly bonded to O); the basis for building complex carbohydrates and requires the anomeric carbon to link to another sugar

glycosidic bonding between two monosaccharide subunits

repeated monosaccharide or polysaccharide glycosidic bonding

sucrose (glucose-α-1,2-fructose)

lactose (galactose-β-1,4-glucose)

maltose (glucose-α-1,4-glucose)

a polysaccharide which is the main structural component for plant cell walls and is a main source of fiber in the human diet; linked by β-1,4 glycosidic bonds

polysaccharides which function as a main energy storage form for plants

a polysaccharide which functions as a main energy storage form for animals; linked by α-1,4 glycosidic and α-1,6 glycosidic bonds; very highly branched

an aldohexose (meaning it has one aldehyde group and six carbons); has 4 chiral carbons (16 stereoisomers)

a rearrangement of bonds

cleaves amylose at the nonreducing end of the polymer to yield maltose exclusively

cleaves amylose anywhere along the chain to yield short polysaccharides, maltose and glucose

removes oligosaccharides from a branch in glycogen or starches

yields glucose 1-phosphate

type of starch linked via α-1,4 glycosidic bonds and α-1,6 glycosidic bonds; highly branched

type of starch linked via α-1,4 glycosidic bonds

cyclic forms of monosaccharides