Carbohydrates

Question 1

Stereoisomers

Answer 1

Same chemical formula but differ in spatial arrangement

Question 2

Carbohydrate Enantiomers

Answer 2

Nonsuperimposable mirror images; Same sugars in different optical families (D or L)

Question 3

Carbohydrate Diastereomers

Answer 3

Two sugars in the same family

Question 4

Epimers

Answer 4

Differ in configuration at exactly one chiral center

Question 5

Alpha Anomer

Answer 5

Diastereoisomers of cyclic forms of sugars or similar molecules differing in the configuration at the anomeric carbon (C-1 atom of an aldose or the C-2 atom of a 2-ketose)

**OH group is trans (pointing down) to CH2OH

Question 6

Beta Anomer

Answer 6

Diastereoisomers of cyclic forms of sugars or similar molecules differing in the configuration at the anomeric carbon (C-1 atom of an aldose or the C-2 atom of a 2-ketose)

**OH group cis (pointing up) to CH2OH

Question 7

Mutarotation

Answer 7

Spontaneous change of molecule between the Alpha anomer and Beta anomer (straight chain molecule is the intermediate)

Question 8

Tollen’s Reagent

Answer 8

Uses Ag(NH3)2 (+) as an oxidizing agent to test the presence of reducing agents and sugars

Aldehydes reduce Ag+ to Ag metallic silver

Question 9

Benedict’s Reagent

Answer 9

Aldehydes are oxidized and Cu2O (red) precipitate is formed to test presence of reducing agents and sugars

Question 10

Tautomerization

Answer 10

Rearrangement of bonds (move it to form a double bodn)

Question 11

Esterification

Answer 11

Sugar + COOH (or derivative) —-> Ester (ROOR)

Question 12

Phosphorylation

Answer 12

Transfer PO3 from ATP on to the sugar —-> Phosphate ester

Question 13

Glycoside Formation

Answer 13

Dehydration rxn where the Anomeric carbon link to another sugar (C-O bond) - this is the basis for forming complex carbs

Question 14

Alpha or Beta- 1, 6 Linkage

Answer 14

1, 6 means C1 of first sugar + C6 of 2nd sugar are attached

Alpha = OH on C1 is below glucose ring plane

Beta = OH on C1 is above the glucose ring plane

Question 15

Polysaccharides

Answer 15

Long chains of monosaccharides linked together by glycosidic bonds

Question 16

Cellulose

Answer 16

Polysaccharide that usually contain Beta - D - glucose with Beta - 1, 4 glycosidic links

*Main structural component in plants

Question 17

Alpha or Beta - 1, 4 Linkage

Answer 17

1, 4 means C1 of first sugar + C4 of 2nd sugar are attached

Alpha = OH on C1 is below glucose ring plane

Beta = OH on C1 is above the glucose ring plane

Question 18

Starch

Answer 18

Alpha - D - Glucose

Main energy store for plants

Question 19

Amylose

Answer 19

Type of starch composed of:

Linear glucose polymer with Alpha - 1, 4 glycosidic links

Question 20

Amylopectin

Answer 20

Type of starch composed of:

Amylose (Alpha - 1, 4 glycosidic links ) and Alpha - 1, 6 glycosidic links

Question 21

Glycogen

Answer 21

Alpha - 1, 6 glycosidic bonds that are highly branched

Carbohydrate storage system in animals

Question 22

Trioses

Answer 22

3-Carbon sugars

Question 23

Tetroses

Answer 23

4-Carbon sugars

Question 24

Aldoses

Answer 24

Sugars with aldehydes as their most oxidized group

Question 25

Ketoses

Answer 25

Sugars with ketones as their most oxidized group

Question 26

Anomeric Carbon

Answer 26

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

Question 27

Deoxy Sugars

Answer 27

When an H replaces an OH group on a sugar

Question 28

Sucrose

Answer 28

Type of disaccharide: Glucose - Alpha - 1, 2 Fructose

Question 29

Lactose

Answer 29

Type of disaccharide: Galactose - Beta - 1, 4 Glucose

Question 30

Maltose

Answer 30

Type of disaccharide: Glucose - Alpha - 1, 4 Glucose