Carbohydrates Flashcards
What are five functions of carbohydrates?
Energy source and storage
Structural components of cell walls
Lubricant
Protection
Communication in cell-cell signaling
What is an aldehyde/aldose?
Carbonyl group is located at the end of a carbon chain
What is a ketone/ketose?
Carbonyl group is located in any other position
What are stereoisomers?
Compounds with the same composition and the same order of atomic connections but different molecular arrangements in space
What is an enantiomer?
Pairs of stereoisomers that are mirror images of one another but cannot be superimposed on each other
What type of isomer of monosaccharides exists in living organisms?
D isomers
E.g. Dextrose (D-glucose)
What are diastereomers?
Pairs of stereoisomers that are not mirror images of each other
What are epimers?
Two sugars that differ only in configuration around one carbon atom
E.g. Galactose is an epimer of glucose at C-4
Mannose is an epimer of glucose at C-2
What is a pyranose?
6-sided ring structure of a monosaccharide
What is a furanose?
5-sided ring structure of a monosaccharide
How is a hemiacetal formed?
Through the addition of an -OH group to the aldehyde in a monosaccharide
How is a hemiketal formed?
Through the addition of an -OH group to the ketone of a monosaccharide
What is an anomer?
Isomeric forms of monosaccharide that differ in configuration about the C1 carbon
What is the anomeric carbon?
The former carbonyl carbon (C1) in the chain form of the monosaccharide that becomes the new chiral carbon in the ring structure
What is configuration a of a monosaccharide ring?
If the -OH group on opposite side of the ring as CH2OH
What is configuration B of a monosaccharide ring?
If the -OH group ends up on the same side of the ring
What ring configuration is most often found in nature?
B form
What is a glycosidic bond?
Bond formed through the addition of an alcohol group to and aldehyde or ketone (C-O)
What can hydrolyze glycosidic bonds?
Acids
What are glycosidic bonds resistant to?
Cleavage by base
What is a reducing sugar?
Sugar that has a free anomeric carbon and can be reduced
E.g. all monosaccharides, Lactose and Maltose
What are polysaccharides?
Natural carbohydrates usually occur as polymers
Can be homo-, hetero-, linear or branched
Do not have a defined molecular wight
Synthesis intrinsic to enzymes that catalyze polymerization of monomeric units
What is starch?
Storage polysaccharide in plants
polymers of glucose
What is amylose?
Unbranched starch polymer
a1-4 linkages
