Chem 2B Ch. 10 Carbohydrates

Front 1

What is the formula for glucose?

Back 1

C₆H₁₂O₆

Front 2

What do the structures of carbohydrates have in common?

Back 2

many hydroxyl groups on adjacent carbons together with either an aldehyde or ketone group.

Front 3

A member of a large class of naturally occurring polyhydroxy aldehydes and ketones.

Back 3

carbohydrates

Front 4

A carbohydrate with three to seven carbon atoms.

Back 4

Monosaccharide (simple sugar)

Front 5

What are the simplest carbohydrates?

Back 5

monosaccharides aka simple sugars

Front 6

How many aldehyde or ketone functional groups do monosaccharides have?

Back 6

Any one monosaccharide has only one aldehyde or ketone functional group.

Front 7

If the monosaccharide has an aldehyde group, it is classified as:

Back 7

an aldose

Front 8

If the monosaccharide has a ketone group, it is classified as:

Back 8

a ketose

Front 9

A monosaccharide that contains an aldehyde carbonyl group.

Back 9

aldose

Front 10

A monosaccharide that contains a ketone carbonyl group.

Back 10

ketose

Front 11

Where is the aldehyde group of an aldose always located?

Back 11

at the end of the carbon chain

Front 12

Where is the ketone group of a ketose always located?

Back 12

on the second carbon of the chain

Front 13

Regardless of whether a sugar is an aldose or ketose, what is on the opposite end of the carbon chain from the aldehyde or ketone groups?

Back 13

a -CH₂OH group

Front 14

Describe the location of hydroxyl groups in an aldose molecule?

Back 14

There are hydroxyl groups on every carbon atom between the carbonyl carbon atom and the -CH₂OH group.

Front 15

Describe the location of hydroxyl groups in a ketose molecule?

Back 15

There are hydroxyl groups on every carbon atom from the -CH₂OH group up to, but not including the ketone group.

Front 16

How are simple sugars aka monosaccharides named?

Back 16

simple sugars are known by common names like glucose, ribose, and fructose rather than by IUPAC names.

Front 17

The family name ending in -ose indicates:

Back 17

a carbohydrate

Front 18

The number of carbon atoms in an aldose or ketose is specified by:

Back 18

the prefixes: tri, tetra, penta, hexa, and hepta, which are placed before the ending, -ose.

Front 19

How many carbons does glucose have?

Back 19

6; glucose is an aldohexose

Front 20

How many carbons does fructose have?

Back 20

6; fructose is a ketohexose

Front 21

How many carbons does ribose have?

Back 21

5; ribose is an aldopentose

Front 22

Most naturally occurring simple sugars have what functional group and how many carbons?

Back 22

most naturally occurring simple sugars are aldehydes with five or six carbons.

Front 23

Monosaccharides react with each other to form:

Back 23

disaccharides and polysaccharides

Front 24

Disaccharide

Back 24

A carbohydrate composed of two monosaccharides.

Front 25

Polysaccharide(complex carbohydrate)

Back 25

A carbohydrate that is a polymer of monosaccharides.

Front 26

Describe two important aspects of monosaccharide structure:

Back 26

1) Monosaccharides are chiral molecules
2) Monosaccharides exist mainly in cyclic, rather than straight-chain forms.

Front 27

What is the simplest naturally occurring carbohydrate? Name it according to its number of carbon atoms.

Back 27

glyceraldehyde, an aldotriose

Front 28

Like all enantiomers, the two forms of glyceraldehyde have the same physical properties except for:

Back 28

the way in which they affect polarized light.

Front 29

Diastereomers

Back 29

Stereoisomers that are not mirror images of each other.

Front 30

By convention, the carbonyl group and the terminal CH₂OH are drawn pointing to the:

Back 30

right, it is understood that the bonds between those carbon atoms and the other carbon atoms rotate freely and do not affect the symmetry of the molecule.

Front 31

What is the formula for the maximum number of possible stereoisomers a chiral compound can have?

Back 31

2ⁿ ; where n is the number of chiral carbon atoms.

Front 32

What is the formula for the maximum number of possible enantiomers a chiral compound can have?

Back 32

2ⁿ÷2; where n is the number of chiral carbon atoms.

Front 33

In Fischer projection, the intersection of two crossed lines represents:

Back 33

a chiral carbon

Front 34

In Fischer projection, horizontal lines represent:

Back 34

bonds pointing TOWARD YOU.

Front 35

In Fischer projection, vertical lines represent:

Back 35

bonds pointing AWAY FROM YOU.

Front 36

The bold solid wedges and dashed lines used to indicate 3-D structure used until now represent:

Back 36

Solid wedges represent bonds coming OUT AT YOU and dashed lines represent bond pointing AWAY FROM YOU.

Front 37

solid wedges are to coming out at you as Fischer projection is to:

Back 37

horizontal lines

Front 38

dashed lines are to pointing away from you as Fischer projection is to:

Back 38

vertical lines.

Front 39

Define a D Sugar:

Back 39

A monosaccharide with the -OH group on the chiral carbon atom farthest from the carbonyl group pointing to the right in a Fischer projection.

Front 40

Define an L Sugar:

Back 40

A monosaccharide with the -OH group on the chiral carbon atom farthest from the carbonyl group pointing to the left in a Fischer projection.

Front 41

Which family do most carbohydrates belong? Left or Right?

Back 41

Right

Front 42

The designations L and D derive from the Latin words:

Back 42

"levo" for left and "dextro" for right.

Front 43

D-Glucose is also called:

Back 43

dextrose or blood sugar

Front 44

What are some important facts about D-Glucose?

Back 44

-Is the most abundant of all monosaccharides
-source of energy to fuel biochemical reactions in nearly all living organisms.
-Stored as starch in plants and glycogen in animals.

Front 45

Monosaccharides with 5 to 6 carbons, like D-Glucose exist primarily in this form in solution:

Back 45

a cyclic form

Front 46

The cyclic forms of D-Glucose differ only at:

Back 46

The hemiacetal carbon, where the -OH group is either on the same or opposite side from the CH₂OH group.

Front 47

Cyclic D-Glucose with the hemiacetal -OH group on the SAME side as the CH₂OH group is labelled as:

Back 47

β-D-Glucose

Front 48

Cyclic D-Glucose with the hemiacetal -OH group on the OPPOSITE side as the CH₂OH group is labelled as:

Back 48

α-D-Glucose

Front 49

What are the steps to converting a Fischer projection into a cyclic form?

Back 49

1) Lay the Fischer Projection down with C1 to the right and the other curled around the back.
2) The single bond between C4 and C5 is rotated so that the -CH₂OH group is vertical.
3) Finally, the hemiacetal O-R bond is formed by bonding the oxygen from the -OH group on C5 to C1, and the H from the -OH group on C5 to the carbonyl oxygen of C1.

Front 50

Describe hemiacetal formation:

Back 50

The H from the alcohol bonds to the carbonyl-group oxygen, and the OR from the alcohol bonds to the carbonyl-group carbon.

Front 51

Which monosaccharides form cyclic hemiacetals?

Back 51

monosaccharides with five or six carbon atoms.

Front 52

The cyclic structures of monosaccharides are called:

Back 52

Hayworth projections

Front 53

When drawing Hayworth projections, -OH groups on the LEFT side in Fischer projections are drawn:

Back 53

pointing up

Front 54

When drawing Hayworth projections, -OH groups on the RIGHT side in Fischer projections are drawn:

Back 54

pointing down

Front 55

In α forms of cyclic sugars, the hemiacetal -OH group is pointed:

Back 55

down

Front 56

In β forms of cyclic sugars, the hemiacetal -OH group is pointed:

Back 56

up

Front 57

What are the two forms of cyclic sugars?

Back 57

α and β forms.

Front 58

Cyclic monosaccharides that differ only in the positions of substituents at the hemiacetal carbon are known as________ and the hemiacital carbon is said to be:

Back 58

anomers; an anomeric carbon

Front 59

Are the α and β anomers of a cyclic sugar enantiomers?

Back 59

No, they are not mirror images.

Front 60

Although the structural difference between anomers appears small, it has enormous biological consequences such as:

Back 60

the vast difference in digestibility of starch and cellulose

Front 61

A change in rotation of plane-polarized light resulting from the equilibrium between cyclic anomers and the open-chain form of a sugar.

Back 61

Mutarotation

Front 62

What are the properties of monosaccharides?

Back 62

-can form multiple H bonds through their hydroxyl groups.
-high-melting, white, crystalline solids.
-soluble in water, insoluble in nonpolar solvents.

Front 63

A carbohydrate that reacts in basic solution with a mild oxidizing agent.

Back 63

Reducing sugar

Front 64

A cyclic acetal formed by reaction of a monosaccharide with an alcohol, accompanied by loss of HOH.

Back 64

Glycoside

Front 65

What is a Glycosidic bond?

Back 65

The Bond between the anomeric carbon atom of a monosaccharide and an -OR group.

Front 66

Can both aldoses and ketoses undergo oxidation?

Back 66

Yes. In basic solution, ALL monosaccharides are reducing sugars.

Front 67

Describe the formation of an enediol:

Back 67

An enediol is is formed when a ketone with a hydrogen atom on the carbon adjacent to the carbonyl carbon moves to the carbonyl oxygen when reacted with a base. The carbonyl oxygen becomes a hydroxyl group and the double bond it rearranged and formed between the carbonyl carbon and the adjacent carbon.

Front 68

The shift of the hydrogen atom and the double bond in the formation of the enediol is called:

Back 68

keto-enol tautomerism

Front 69

Describe the reaction of a ketose to form an aldonic acid anion/ carboxylic acid

Back 69

ketose in a two way reaction, reacts with OH⁻ to become an enediol. The enediol, in a two way reaction reacts with OH⁻ to become an aldose. The aldose reacts with an oxidizing agent to become an aldonic acid/carboxylic acid.

Front 70

Describe the formation of an acetal:

Back 70

The H from the hemiacetal OH group is replaced by the -R group of the alcohol. The H from the hemiacital forms water with the -OH group from the alcohol.

Front 71

What is the reaction of the formation of an acetal?

Back 71

aldehyde or ketone + alcohol (acid catalyst) ⇌ hemiacetal + alcohol (acid catalyst) ⇌
an acetal + HOH

Front 72

The acetals formed from cyclic monosaccharides are called:

Back 72

glycosides

Front 73

What -OH group in the cyclic monosaccharide reacts to form a glycoside?

Back 73

the -OH group on the anomeric carbon.

Front 74

A cyclic acetal formed from any sugar is called a ________, but a cyclic acetal formed from glucose is called:

Back 74

A cyclic acetal formed from any sugar is called a GLYCOSIDE, but a cyclic acetal formed from glucose is called a GLUCOSIDE.

Front 75

The bond between an anomeric carbon and the ether-like group in a glycoside is called:

Back 75

a glycosidic bond

Front 76

Are glycosides reducing sugars?

Back 76

No

Front 77

In disaccharides and polysaccharides, monosaccharides are connected to each other by:

Back 77

glycosidic bonds

Front 78

A disaccharide forms by the reaction between these groups:

Back 78

through the reaction of the anomeric carbon of one monosaccharide to the -OH group of another monosaccharide, forming an acetal.

Front 79

Draw and name the reaction of α-D-Glucose and methanol:

Back 79

The reaction is α-D-Glucose + CH₃OH (H⁺)→
Methyl α-D-Glucose + water Name: Methyl α-D-Glucoside

Front 80

What are the disaccharides studied?

Back 80

sucrose, lactose, and maltose

Front 81

A glycosidic link between the hemiacetal hydroxyl group at C1 of one sugar and the hydroxyl group at C4 of another sugar.

Back 81

1,4 Link

Front 82

The α 1,4 Link points ________, while the β 1,4 link points _______.

Back 82

The α 1,4 Link points DOWN, while the β 1,4 link points UP.

Front 83

Which type of link does each sugar have: sucrose, lactose, and maltose?

Back 83

sucrose = an anomeric link
lactose = β-1,4 link
maltose = α-1,4 link

Front 84

Sucrose is composed of:

Back 84

α-D-Glucose and a β-D-Fructose

Front 85

Lactose is composed of:

Back 85

β-D-Glucose and β-D-Galactose

Front 86

Maltose is composed of:

Back 86

two α-D-Glucose molecules

Front 87

Is Maltose a reducing sugar?

Back 87

yes, it is both an acetal and a hemiacital

Front 88

Is lactose a reducing sugar?

Back 88

yes

Front 89

Is sucrose a reducing sugar?

Back 89

No, because it has no hemiacetal group.

Front 90

Describe the reaction of monosaccharides with oxidizing agents:

Back 90

Only straight chain monosaccharides (both aldehydes and ketones) are oxidized into carboxylic acids.

Front 91

Oxidation of an aldehyde is:

Back 91

the addition of an oxygen atom to the H bound to the carbonyl carbon.

Front 92

What are the two most abundant polysaccharides in the world?

Back 92

cellulose and chitin

Front 93

Describe chitin:

Back 93

it is a hard, structural polymer of N-acetyl-D-glucosamine subunits. The shells of lobsters, beetles, and spiders are made of chitin.

Front 94

A protein that contains a short carbohydrate chain.

Back 94

Glycoprotein.

Front 95

How is the carbohydrate connected to the protein in a glycoprotein?

Back 95

by a glycosidic bond between the anomeric carbon and a side chain of the protein. The bond is either a C-N glycosidic bond or a C-O glycosidic bond.

Front 96

Three of the most important polysaccharides are:

Back 96

cellulose, starch, and glycogen

Front 97

Cellulose is made up of what monosaccharides and links?

Back 97

cellulose is made up of thousands of β-D-Glucose units joined in a long, straight chain by β-1,4 links.

Front 98

What are the two types of starch?

Back 98

amylose(20%) and amylopectin(80%)

Front 99

Describe what amylose is made up of:

Back 99

amylose is made up of several hundred to a thousand α-D-Glucose units linked in long chains by α-1,4 glycosidic bonds.
-coils into helices
-hot water soluble

Front 100

Describe what amylopectin is made up of:

Back 100

amylopectin is made up of 100,000 α-D-Glucose units linked in long chains by α-1,4 links with α-1,6 links every 25 units.
-not water soluble

Front 101

Starch molecules are digested mainly in the ________ by the enzyme _________ which catalyses hydrolysis of__________.

Back 101

Starch molecules are digested mainly in the small intestine by the enzyme α-mylase which catalyses hydrolysis of the α-1,4 link.

Front 102

Describe what glycogen is made of:

Back 102

The longest polymer of all the polysaccharides studied; up to 1 million α-D-Glucose units with α-1,4 links and α-1,6 links similar to amylopectin.