BB 450 3 questions with complete
solutions rated A+
Monosaccharides - correct answer ✔✔-most common include glucose, fructose, galactose,
ribose, and mannose.
-Of these sugars, all but one (fructose) exists as an aldehyde.
-Fructose and other less well-known sugars are ketones
Diastereomers - correct answer ✔✔-Two sugars having the same chemical form (aldoses, for
example) and the same number of carbons, but that differ only in the stereochemical
orientations of their carbons
-For example, glucose, galactose, and mannose all have the formula of C6H12O6, but are
chemically distinct from each other in the orientation of hydroxyl groups around the carbons
within them.
Nomenclature of Carbohydrates - correct answer ✔✔-'ose': flags a molecule as a sugar.
-prefix that tells how many carbons the sugar contains:
•Tri- = 3 •Tetr- = 4 •Pent- = 5 •Hex- =6 •Hept- = 7 •Oct- = 8
-identify whether the sugar contains an aldehyde group (aldo-) or a ketone (keto-) group
epimers - correct answer ✔✔-If two sugars are identical except for having one hydroxyl
configured differently (such as glucose and galactose, they are diastereomers known as epimers
Enantiomers - correct answer ✔✔-If the configuration of all of the hydroxyls of one sugar is
exactly the opposite of their configuration in another sugar, the two sugars are mirror images of
each other. Mirror images of sugars are known as enantiomers
, anomeric carbon - correct answer ✔✔Sugars with five and six carbons can readily cyclize and
when they do, a new asymmetric carbon is created that didn't exist in the same sugars when
they were in the straight chain form.
-can have the hydroxyl in two different positions. These positions are referred to as α and β
furanoses - correct answer ✔✔Sugars cyclizing to form rings with five atoms in them
pyranoses - correct answer ✔✔forming rings with six atoms, such as glucose
glycoside - correct answer ✔✔-linking the anomeric hydroxyl to another group
-will remain locked in whichever α- or β- configuration they were in when the anomeric
hydroxyl was altered
Boat/chair conformations - correct answer ✔✔-Orbitals of carbon prefer to be in tetrahedral
conformations and this means that the bonds between carbons in a ring do not lie flat.
-rings "pucker" to try to accommodate this tendency, giving rise to different 3D forms for any
given sugar
-The stablest (and thus most abundant) of these forms have all of the hydoxyls in the equatorial
positions, resulting in less steric hindrance.
Modified monosaccharides - correct answer ✔✔-Common ones include oxidation, reduction,
phosphorylation, and substitution of an amine or an acetylamine for a hydroxy
-The ones that affect the anomeric hydroxyl group make glycosides
Oxidation/reduction - correct answer ✔✔Sugars that are readily oxidized are called 'reducing
sugars' because their oxidation causes other reacting molecules to be reduced.
-A test for reducing sugars is known as Benedict's test.
+In it, sugars are mixed and heated with an alkaline solution containing Cu++.
solutions rated A+
Monosaccharides - correct answer ✔✔-most common include glucose, fructose, galactose,
ribose, and mannose.
-Of these sugars, all but one (fructose) exists as an aldehyde.
-Fructose and other less well-known sugars are ketones
Diastereomers - correct answer ✔✔-Two sugars having the same chemical form (aldoses, for
example) and the same number of carbons, but that differ only in the stereochemical
orientations of their carbons
-For example, glucose, galactose, and mannose all have the formula of C6H12O6, but are
chemically distinct from each other in the orientation of hydroxyl groups around the carbons
within them.
Nomenclature of Carbohydrates - correct answer ✔✔-'ose': flags a molecule as a sugar.
-prefix that tells how many carbons the sugar contains:
•Tri- = 3 •Tetr- = 4 •Pent- = 5 •Hex- =6 •Hept- = 7 •Oct- = 8
-identify whether the sugar contains an aldehyde group (aldo-) or a ketone (keto-) group
epimers - correct answer ✔✔-If two sugars are identical except for having one hydroxyl
configured differently (such as glucose and galactose, they are diastereomers known as epimers
Enantiomers - correct answer ✔✔-If the configuration of all of the hydroxyls of one sugar is
exactly the opposite of their configuration in another sugar, the two sugars are mirror images of
each other. Mirror images of sugars are known as enantiomers
, anomeric carbon - correct answer ✔✔Sugars with five and six carbons can readily cyclize and
when they do, a new asymmetric carbon is created that didn't exist in the same sugars when
they were in the straight chain form.
-can have the hydroxyl in two different positions. These positions are referred to as α and β
furanoses - correct answer ✔✔Sugars cyclizing to form rings with five atoms in them
pyranoses - correct answer ✔✔forming rings with six atoms, such as glucose
glycoside - correct answer ✔✔-linking the anomeric hydroxyl to another group
-will remain locked in whichever α- or β- configuration they were in when the anomeric
hydroxyl was altered
Boat/chair conformations - correct answer ✔✔-Orbitals of carbon prefer to be in tetrahedral
conformations and this means that the bonds between carbons in a ring do not lie flat.
-rings "pucker" to try to accommodate this tendency, giving rise to different 3D forms for any
given sugar
-The stablest (and thus most abundant) of these forms have all of the hydoxyls in the equatorial
positions, resulting in less steric hindrance.
Modified monosaccharides - correct answer ✔✔-Common ones include oxidation, reduction,
phosphorylation, and substitution of an amine or an acetylamine for a hydroxy
-The ones that affect the anomeric hydroxyl group make glycosides
Oxidation/reduction - correct answer ✔✔Sugars that are readily oxidized are called 'reducing
sugars' because their oxidation causes other reacting molecules to be reduced.
-A test for reducing sugars is known as Benedict's test.
+In it, sugars are mixed and heated with an alkaline solution containing Cu++.
