chemistry 8.1-carbohydrates-monosaccharides
TRANSCRIPT
![Page 1: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/1.jpg)
Chapter 8 (part 1)
Carbohydrates
![Page 2: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/2.jpg)
Carbohydrates• Most abundant class of
biological molecules on Earth• Originally produced through
CO2 fixation during photosynthesis
![Page 3: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/3.jpg)
Roles of Carbohydrates• Energy storage
(glycogen,starch)• Structural components
(cellulose,chitin)• Cellular recognition • Carbohydrate derivatives include
DNA, RNA, co-factors, glycoproteins, glycolipids
![Page 4: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/4.jpg)
Carbohydrates• Monosaccharides (simple
sugars) cannot be broken down into simpler sugars under mild conditions
• Oligosaccharides = "a few" - usually 2 to 10
• Polysaccharides are polymers of the simple sugars
![Page 5: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/5.jpg)
Monosaccharides• Polyhydroxy ketones
(ketoses) and aldehydes (aldoses)
• Aldoses and ketoses contain aldehyde and ketone functions, respectively
• Ketose named for “equivalent aldose” + “ul” inserted
• Triose, tetrose, etc. denotes number of carbons
• Empirical formula = (CH2O)n
C
C*
O
C*
C*
CH2OH
H OH
HO H
H OH
HCH2OH
C
C*
C*
CH2OH
O
HO H
H OH
D-ribose D-ribulose
![Page 6: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/6.jpg)
Monosaccharides are chiral
• Aldoses with 3C or more and ketoses with 4C or more are chiral
• The number of chiral carbons present in a ketose is always one less than the number found in the same length aldose
• Number of possible steroisomers = 2n (n = the number of chiral carbons)
C
C*
O
C*
C*
C*
CH2OH
H OH
HO H
H OH
H OH
HCH2OH
C
C*
C*
C*
CH2OH
O
HO H
H OH
H OH
D-glucose D-fructose
![Page 7: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/7.jpg)
Stereochemistry
•Enantiomers = mirror images•Pairs of isomers that have opposite configurations at one or more chiral centers but are NOT mirror images are diastereomers •Epimers = Two sugars that differ in configuration at only one chiral center
C
C*
O
C*
C*
C*
CH2OH
H OH
HO H
H OH
H OH
HC
C*
O
C*
C*
C*
CH2OH
HO H
H OH
HO H
HO H
H
C
C*
O
C*
C*
C*
CH2OH
H OH
HO H
H OH
H OH
HC
C*
O
C*
C*
C*
CH2OH
HO H
HO H
H OH
H OH
HC
C*
O
C*
C*
C*
CH2OH
HO H
HO H
H OH
H OH
HC
C*
O
C*
C*
C*
CH2OH
H OH
HO H
HO H
H OH
H
D-glucoseL-glucose
Enantiomers
D-glucose D-mannose
Epimers
D-mannose D-galactose
Diastereomers
![Page 8: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/8.jpg)
Cyclization of aldose and ketoses introduces additional
chiral center• Aldose sugars (glucose) can cyclize to
form a cyclic hemiacetal
• Ketose sugars (fructose) can cyclize to form a cyclic hemiketal
HC
R1
O
OH R2
HO
C*
OR2
R1H
H
ALCOHOL
ALDEHYDE
HEMIACETAL
NEW CHIRAL CARBON
RC
R1
O
OH R2
HO
C*
OR2
R1R
H
ALCOHOL
KETONE
HEMIKETAL
NEW CHIRAL CARBON
![Page 9: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/9.jpg)
Haworth Projections
Anomeric carbon(most oxidized)
-OH up = beta-OH down = alpha
1
23
4
5
6
For all non-anomeric carbons, -OH groups point down in Haworth projections if pointing right in Fischer projections
C1
C2 OHH
HO
C3
C4
C5
CH2OH
HHO
OHH
OHH
![Page 10: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/10.jpg)
Monosaccharides can cyclize to form Pyranose / Furanose
forms = 64% = 36%
= 21.5% = 58.5%
= 13.5% = 6.5%
![Page 11: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/11.jpg)
Conformation of Monosaccharides
Pyranose sugars not planar molecules, prefer to be in either of the two chair conformations.
![Page 12: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/12.jpg)
Reducing Sugars
• When in the uncyclized form, monosaccharides act as reducing agents.
• Free carbonyl group from aldoses or ketoses can reduce Cu2+ and Ag+ ions to insoluble products
![Page 13: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/13.jpg)
![Page 14: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/14.jpg)
Derivatives of Monosaccharides
![Page 15: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/15.jpg)
Sugar Phosphates
![Page 16: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/16.jpg)
Deoxy Acids
![Page 17: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/17.jpg)
Amino Sugars
![Page 18: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/18.jpg)
Sugar alcohols
![Page 19: Chemistry 8.1-Carbohydrates-monosaccharides](https://reader031.vdocuments.site/reader031/viewer/2022012914/589afc4c1a28ab3e288b6d3b/html5/thumbnails/19.jpg)
Monosaccharide structures you need to
know• Glucose• Fructose• Ribulose• Glyceraldehyde• Dihydroxyacetone