2Monosaccharides Flashcards
Base all sugars on which molecule?
D-Glyceraldehyde
CHO
l
H- C - OH*
l
CH2O
Most sugars are _____handed sugar
Right-handed
Aldose sugars have ____
Aldehyde group
Remember the six types of aldose sugars:
(3) D – glyceraldehyde,
(4) D – erythrose,
(5) D – ribose,
(6) D – glucose, D – mannose, D – galactose
D-Erythrose structure (4)
H O
\ //
H-C-OH
l
H-C-OH*
l
CH2OHD-Threose structure (4)
H O
\ //
C
l
OH-C-H
l
H- C- OH*
l
CH2OHD-Ribose structure(5)
H O
\ //
C
l
H-C-OH*
l
H-C-OH*
l
H-C-OH*
l
CH2OHD-Arabinose
Just know similar to ribose
H O
\ //
C
l
HO-C-H
l
H- C-OH
l
H- C-OH
l
CH2OH
D-Xylose structure (5)
Just remember similar to ribose
H O
\ //
C
l
H-C-OH
l
HO-C-H
l
H- C-OH
l
CH2OH
The reference compound for naming D and L isomers of sugars is:
Glyceraldehyde
D-Glucose structure
R-L-R-R
H O
\ //
C
l
H- C-OH
l
OH-C-H
l
H- C-OH
l
H- C-OH
l
CH2OHD- Mannose structure
(Only c#2 changed from glucose)
LLRR
H O
\ //
C
l
HO-C-H
l
HO-C-H
l
H- C-OH
l
H- C-OH
l
CH2OHD-Galactose (6Carbons)
C#4 is different
RLLR
H O
\ //
C
l
H-C-OH
l
HO-C-H
l
HO-C-H
l
H- C-OH
l
CH2OHWhat is epimeric pair?
D- glucose and D-mannose
Two major classes- the Aldose and ketose sugars
Glyceraldehyde (an aldotriose)
H O
\ //
C
l
H- C-OH
l
H- C-OH
l
H
Dihydroxyacetone (a ketotriose)
H
l
H- C-OH
l
C=O
l
H- C-OH
l
H
Ketose Sugars-2 structures to know
Dihydroxyacetone (3 carbons) CH2OH l C=O l CH2OH
D-fructose (6carbon)
CH2OH
l
C=O
l
HO-C-H
l
H- C-OH
l
H- C-OH
l
CH2OH
Similar to glucose except ketone at C#2
Which of the following is an epimeric pair?
2 isomers differ in configuration at one stereo center
D-glucose and D-mannose
Which of the following monosaccharides is not an Aldose?
Fructose
When the linear form of glucose cyclizes, the product is an:
Hemiacetal
Draw glyceraldehyde. How many stereoisomers can there be?
2
Draw glycerol. How many stereoisomers are there?
1
D-glucose is epimeric ex on carbon #2. What did it become?
D-mannose
Is D-2 deoxyglucose the same thing as D-2-deoxygalactose?
No
What biochemical feature is common in cellulose and is not found in glycogen?
Beta 1-4 bonds
Glycogen has alpha 1-4 bond
Which of the following monosaccharides is not an Aldose ?
Fructose
Hemiacetal is made up of:
Aldehyde + Alcohol
Hemiacetal can react with additional alcohols and form…
Acetal + water
This reaction makes it less spontaneous and more stable. Split out water and more difficult.
Ketone + alcohol=
Hemiketal
Hemiketal can react with additional alcohol to form
Ketal
2 glucose molecules react:
Carbon #4 alcohol + hemiacetal carbon #1
Disaccharide form with acetal linkage
Glc(alpha 1➡️4) Glc
Reducing sugar because of the right side of the right sugar it still has a free carbon number one which is a hemiacetal which can still open up to form an aldehyde and therefore still has the ability to become a reducing sugar.
Galactose+ glucose
Lactose
Reducing sugar
Gal(Beta1➡️4) Glc
Galactose is almost identical to glucose but carbon number four is flipped compared to glucose so the OH group will be on top and the H group will be on bottom
Reducing sugar because the hemiacetal on the right still has the anime roc carbon free, carbon#1 is free. Hemiactrals can open up freely to aldehydes.
Glucose + Fructose
Table sugar- sucrose
- not a reducing sugar* both a mimetic carbons tied up in bonding to each other
Glc(alpha1↔️2Beta) Fru
Has an acetal and ketal bond at same time. Glucose c#1 is alpha conformation with OH group coming down from it but connected to anime roc carbon of fructose, which is a ketose) so form a ketone derivative on #2 of fructose.
2 animeric carbons of glucose attached to each other
Trehalose
Not a reducing sugar
Glc(alpha1↔️1 alpha) Glc
Which two sugars is not a reducing sugar?
Sucrose and trehalose
