Carbohydrates 3

Question 1

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 are referred to as

Answer 1

diastereomers

Question 2

For example, glucose, galactose, and mannose all have the formula of C6H12O6, but are chemically distinct from each
other in the orientation of __________ around the carbons within them.

Answer 2

hydroxyl groups

Question 3

chemical formula of glucose, galactose, mannose

Answer 3

C6H12O6

Question 4

If two sugars are identical except for having one hydroxyl configured differently

Answer 4

diastereomers (epimers)

Question 5

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 ________ of each other

Answer 5

mirror images

Question 6

mirror images of sugars are known as

Answer 6

enantiomers.

Question 7

L-glucose is the mirror image
of

Answer 7

D-glucose

Question 8

Sugars with five and six carbons can readily _________

Answer 8

cyclicize

Question 9

Sugars with ______ and _______ carbons can readily cyclize

Answer 9

5 and 6

Question 10

when sugars cyclize, they form a new

Answer 10

asymmetric carbon that didn’t exist in the same sugars when they were in the straight chain form

Question 11

the new asymmetric carbon created from cyclization is

Answer 11

anomeric carbon

Question 12

anomeric carbon can have hydroxyl in ____ positions

Answer 12

two (alpha and beta)

Question 13

Sugars, such as α-D-glucose
and β-D-glucose that differ only in the configuration of the anomeric carbon are referred to as

Answer 13

anomers

Question 14

Sugars cyclizing to form rings with five atoms in them are referred to as

Answer 14

furanoses

Question 15

Sugars cyclizing to form rings with six atoms in them are referred to as

Answer 15

pyranoses

Question 16

The carbonyl carbon becomes the anomeric carbon in the ring by

Answer 16

binding to the oxygen of a hydroxyl

Question 17

Linking the anomeric hydroxyl to another group will create a _______ and it
will remain locked in whichever α- or β- configuration they were in when the anomeric hydroxyl was altered.

Answer 17

glycoside

Question 18

α- and β- forms of a
given sugar can readily “flip” between each form in solution, so long as the anomeric hydroxyl is ______.

Answer 18

free

Question 19

Orbitals of carbon prefer to be in ____________ and this means that the bonds between carbons in a ring do not lie flat.

Answer 19

tetrahedral conformations

Question 20

The stablest (and thus most abundant) of forms have all of the hydroxyls in the equatorial positions, resulting in less
______

Answer 20

steric hindrance

Question 21

The stablest (and thus most abundant) of forms have all of the hydroxyls in the_______, resulting in less steric hindrance

Answer 21

equatorial position

Question 22

common modifications that affect sugar residues

Answer 22

oxidation
reduction
phosphorylation
substitution of an amin group or acetyl-amine for a hydroxyl

Question 23

modifications that affect the anomeric hydroxyl group makes

Answer 23

glycosides

Question 24

different 3D forms of sugar

Answer 24

boat structures
chairs or envelopes