(Dr. McLachlin) (Unit B) Topic Note 7 Flashcards
Monosaccharides
Simplest sugars, have molecular formula (CH2O)n, where n = 3-7
Terminology:
Monosaccharide with:
1. 3 carbons
2. 4 carbons
3. 5 carbons
4. 6 carbons
5. 7 carbons
- Triose
- Tetrose
- Pentose
- Hexose
- Heptose
How are monosaccharides often depicted?
Fischer projections
Aldose
Carbonyl group is at the end of the molecule
* Aldehyde group, hence “aldose”
Ketose
Carbonyl group is not at the end of the molecule
* Ketone group, hence “ketose”
Do all monosaccharides have a carbonyl group?
Yes
* Carbonyl: An oxygen atom double-bonded to carbon
How are carbons in the monosaccharide numbered?
Starting from the end closest to the carbonyl group
Monosaccharides are called D/L based on what?
Orientation of hydroxyl group on the chiral carbon farthest from the carbonyl group
True or False:
Biological sugars are usually L isomers with the hydroxyl group on the right side in a Fischer projection
False, they are usually D isomers
* D isomers have the hydroxyl group on the right side in a Fischer projection
Epimers
Monosaccharides that differ in stereochemistry at only one chiral carbon as Fischer projections
How are cyclic structures (pentoses and hexoses) depicted?
Haworth projections
Anomeric carbon
The carbon of the carbonyl group with reacts with a hydroxyl group to form a ring
What are monosaccharide rings called in stereochemistry?
Alpha or Beta
How is alpha/beta configuration determined?
Comparing the position of hydroxyl formed at the anomeric carbon with the position of the highest-numbered carbon in the molecule
* Beta: Same side
* Alpha: Opposite sides
What type of bond joines two monosaccharides together in a condensation reaction?
O-glycosidic bond
