Chemistry 106 - Chapter 19 Carbohydrates

racemic mixture

Equal amounts of two enantiomers; do not display optical activity.

What is the name of the five-membered carbon ring in which fructose exists

furanose

What is an example of an aldohexose?

glucose

What forms sucrose?

glucose and fructose common household sugar joined by a1 -> b2 glycosidic linkage not a reducing sugar ( no hemiacetal)

What is an example of an aldotriose.

glyceraldehyde

Monosaccharides + alcohol forms

glycosides (cyclic acetals)

What is the anomeric carbon?

hemiacetal carbon of the cyclic form of a monosaccharide the former carbonyl carbon

The cyclic structures of monosaccharides are which of the following?

hemiacetals

What do monosaccharides mostly form in the Haworth projection?

hemiacetals

A β(1 → 4) glycosidic bond is found in which of the following?

lactose

glucose + galactose forms

lactose

What is the form of amylose?

linear; unbranched chains joined by a (1->4) glycosidic linkage

An α(1 → 4) glycosidic bond is found in which of the following?

maltose

Which of the following is obtained as a result of the complete hydrolysis of starch?

maltose

complete hydrolysis of which of the following disaccharides yields a single monosaccharide?

maltose

glucose + glucose forms

maltose

What is a ketose?

monosaccharide with a ketone group

A polysaccharide is a carbohydrate formed by the combination of how many individual units?

more than 10

Is glycoside in equilibrium with the open-chain aldose/ketose precursor?

no

Do Disaccharides form reducing or non reducing sugars

reducing sugars

glucose + fructose forms

sucrose

When is an alditol formed?

when the -CHO group of a monosaccharide is reduced to a CH2OH group (primary alcohols)

Can disaccharides be hydrolyzed?

yes to yield their monosaccharide building blocks

Which of the following compounds are phosphoric anhydrides?

(ii) and (iii) only

What is a Fischer projection?

2D representation showing the configuration of a stereocenter; carbonyl at the top; top and bottom groups point into the page; side groups point out of the page; carbon at the cross is in the plane of the paper.

How many chiral carbons are present in the open-chain form of an aldopentose?

3

How many carbons does triose have?

3 carbons

Oxidation of this structure at which numbered position will produce an aldonic acid?

1 Oxidation will only occur on the aldehyde, aka carbon 1

A disaccharide is a carbohydrate formed by the combination of how many individual units?

2

What forms maltose?

2 glucose units (glucose and glucose) formed during the digestion (hydrolysis) of starch joined by an a(1->4) glycosidic linkage reducing sugar (contains hemiacetal)

How many carbons does tetrose have?

4 carbons

How many carbons does pentose have?

5 carbons

What size ring is a furanose?

5 membered ring containing an oxygen atom

How many carbons does hexose have?

6 carbons

What size ring is a pyranose?

6 membered containing an oxygen atom

Which substance would be classified as an aldohexose?

A

Which substances have an enantiomer with an L-configuration?

A, B, and D

Which of the following is true about the reducing properties of sugars?

All monosaccharides and some disaccharides are reducing sugars

How do you determine D and L monosaccharides?

By considering the chiral carbon farthest from the carbonyl group: L indicates that the -OH group projects to the left. D (derecha) indicates that the -OH group projects to the right.

Which substance has an L-configuration?

C

The configuration at which carbon of a pentose determines if the pentose has the D or L configuration?

C-4

Which substance would be classified as a ketohexose?

D

What is an example of a D monosaccharide?

D - glyceraldehyde

What forms lactose?

D-galactose and D-glucose units found in mammalian milk joined by an B(1->4) glycosidic linkages reducing sugar (contains hemiacetal)

What is an example of a L monosaccharides?

L - glyceraldehyde

What is specific rotation?

The number of degrees by which an optically active compound rotates the plane of polarized light

What does the suffix -ose mean?

The suffix -ose indicates that a molecules is a carbohydrate

What is an aldose?

a monosaccharide with an aldehyde group

Glycosides are examples of which class of compounds?

acetals

Which of the following reacts with sugars to form glycosides?

alcohols

When glucose adopts a pyranose structure which carbon is the anomeric carbon?

c-1

When an aldohexose such as glucose adopts the pyranose structure, which atoms are connected by an oxygen atom?

c-1 and c-5

What is a glycoside?

carbohydrate containing a cyclic acetal functional group

Monosaccharides are

carbohydrate with a single sugar molecule

Which of the following contains β(1 → 4) glycosidic bonds?

cellulose

Oligosaccharides are

combination of 3-10 monosaccharide units

Polysaccharides are

combination of many monosaccharide units

Disaccharides are

combination of two monosaccharide units carbohydrates that contain two sugar units liked together by acetal linkages

What are polysaccharides?

consists of large numbers of monosaccharides, typically glucose, bonded to each other by glycosidic linkages they are acetals all are non-reducing sugars.

What is an example of a ketotriose.

dihydroxyacetone

What is an example of a ketohexose?

fructose