Physiological Roles of Carbohydrates include:
1) Energy
2) Energy Storage
3) Structural Roles
4) Cellular Interaction
5) Cellular Identification
6) Information Transfer (DNA & RNA)
7) Signaling
What are the two major classes of carbohydrates?
– Aldoses (which have aldehyde groups)
– Ketoses (which have ketone groups)
What determines whether a sugar is designated as D or L?
The designation of a sugar as D or L is based on the configuration of the chiral carbon most distant from the carbonyl oxygen. If the chiral carbon most distant from the carbonyl carbon has a OH in its side chain from left or right determines if its D or L.
What are epimers?
Epimers are sugars that differ in configuration at a single chiral carbon.
What is the difference between the Pyran ring and the Furan ring
Pyran-Six-membered sugar ring is a “pyranose”
Furan-Five-membered sugar ring is a “furanose”
α- hydroxyl of anomeric carbon is ______the plane of the sugar.
below
β- hydroxyl of anomeric carbon is _______ the plane of the sugar.
above
In solution, the α and β configurations
interconvert by a process called
__________.
Mutaroation
Mutarotation represents a change in
conformation. T or F?
False, its configuration
Fructose exists in both pyran and furan ring forms. T or F?
True
what is the primary structural linkage in all polymers of monosaccharides called? And what are the two types
-Glycosidic bonds.
- O-glycosidic bonds occur through oxygen.
- N-glycosidic bonds occur through nitrogen.
Nomenclature of a disaccharide specifies:
- The monosaccharides involved in the disaccharide.
- Their ring types (pyran, furan).
- Their configurations (alpha or beta).
- Their linkages (C1-C4, etc).
- The end with a free anomeric carbon is called the reducing end.
5 rules for naming disaccharides (important)
1) Specify the configuration (alpha or beta) at the anomeric carbon of each monosaccharide.
2) Specify the ring form (furan or pyran) of each monosaccharide.
3) The non-reducing sugar has the suffix “osyl”.
4) The reducing sugar has the suffix “ose”.
5) Indicate in parentheses the two carbon atoms joined by the glycosidic bond with an arrow.
What are Homopolysaccharides
Homopolysaccharides are polymers of a single type of monosaccharide.
What are Heteropolysaccharides
Heteropolysaccharides are polymers containing different types of
monosaccharides.
Where is glycogen found in the human body?
Its present in all cells, but most prevalent in skeletal muscle in liver.
What are the key characteristics of cellulose?
Primary component of plant cell walls (fiber)
Accounts for over half of the carbon in the biosphere
Linear homopolysaccharide of glucose residues
Contains β(1→4) glycosidic bonds in a linear arrangement
Amylase cannot hydrolyze these β(1→4) bonds
What is the chemical difference between cellulose and chitin?
The chemical difference between cellulose and chitin is the replacement of hydroxyl group at C2 with acetylated amino
group.
The β 1-4 linkages of cellulose and chitin
allow formation of _____ ________ ________.
long straight chains
The α 1-4 linkages of starch and glycogen
form a _________, ______ _______.
hollow, helical structure
Sugars are also be covalently linked to lipid molecules to form _________.
glycolipids
Where is the central function of glycolipids?
A central function of glycolipids is in the blood group antigens.
What are glycoproteins?
– Proteins with covalently attached sugars.
– The protein constituent is the largest component by weight.
– Serve a variety of biological roles.
What are proteoglycans?
– Protein component is linked to to a particular type of carbohydrate called
a glycosaminoglycan.
– The carbohydrate constituent is the largest component by weight.
– Often serve structural and lubricating functions.
