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
