The Structure of Sugars Flashcards
Carbohydrates always contain…
Carbon, hydrogen and oxygen
Carbohydrates with five or more carbons tend to…
Form rings
Most sugars have a carbon with four or more different groups attached. This means they are…
Chirally active
Carbohydrates contain two or more ? groups
Hydroxide (-OH)
Carbohydrates have either a ? or ? group
Aldehyde or ketone
Carbons are numbered starting from the…
Aldehyde or ketone group
Carbohydrate rings are not flat, but instead form a…
Non-planar chair configuration
If the ring structure results in different stereochemistry at the carbonyl carbon (C1 in aldoses, C2 in ketoses), it is an…
Alpha or beta anomer (but considered the same sugar)
Because most sugars are chirally active, they can form enantiomers (mirror image molecules) in which ? are reversed
H and OH
Chirally active sugars can exist in D and L forms. Most sugars are found in the ? form
D
Stereoisomers where the configuration around one of the non-carbonyl asymmetric carbons differs are known as…
Epimers
Epimers are considered ( the same / different ) sugars
Different
An example of an epimer is galactose, which is a…
C4 epimer of glucose
Disaccharides are polymers of ? sugar molecules
2
Oligosaccharide is a somewhat imprecise term which usually refers to polymers of between X - Y sugars in length
2-10
Sugars are often…
Modified 🛠
The bond formed between a hemiacetal group of one sugar and the oxygen of a hydroxyl group of another is known as a…
Glycosidic bond
Glycosidic bonds are formed by X and broken by Y (type of reaction)
X = Condensation reactions Y = Hydrolysis reactions
Glycosidic bonds between sugars are typically between carbons…
1 and 4 (1,4 glycosidic bond)
There are a huge range of possible carbohydrate structures which arise from variations in (5)…
- Composition
- Branching
- Multiple glycosylation sites
- Isomeric forms
- Sialic acids
