Carbohydrates Flashcards
What are the properties of monosaccharides
Very water soluble, sweet, have a carbonyl group which us an aldehyde or a ketone and has at least 2 carbons with a hydroxyl group
What are epimers
When a pair of sugars are identical except for the chirality at one carbon atom
Are special cases of diastestromers
Any aldehyde + an alcohol =
Hemiacetal
Alchohol + ketone =
Hemiketal
What is mutarotation
The change in the optical rotation because of the change in the equilibrium between two anomers
Solid glucose is found in the a or b for of the hemiacetal
What are the two types of rings sugars can form when crystallized
Pyranose: a 6 membered ring called a pyran. Hexose sugar eg. Glucose
Furanose: 5 membered ring called a furan. Pentise sugar eg. Ribose
What are reducing sugars
Reducing sugars are oxidized by the cu 2+ ions , becomes cu+. The cu then precipitates out of solution as a eust colored Cu2O
Which carbon of the sugar is most reactive and why
The anomeric carbon. Is bonded to two oxygen atoms, this makes it very electrophilic and reactive
What differentiates a reducing sugar and a non reducing sugar (in terms of structure)
If two sugars are linked head to tail, they can still form a free aldehyde group at its head group. Eg lactose. If two sugars are connected head to head, not a reducing sugar. Eg. Sucrose
What are glycosides
Most important reaction for a sugar, is a condensation reaction
Glycosidic bond: C-O -> alcohol
Glycosilic bond: C-N -> amine
What is a disaccharide
Built from 2 simple sugars
Eg. Sucrose
What are polysaccharides and what are the two types
Are highly branched because sugars have several OH groups and each act as a nucleophile to form a glycosidic bond
Homopolysaccharides: made from a single type of sugar eg: starch, glucagon, cellulose, chitin
Heteropolysaccharides: sugars built from two or more kinds of sugars
What are the three types of sugars
Monosaccharides: simple with only one sugar unit
Disaccharides: two or more sugars
Polysaccharides: polymers of 20 or more sugar units
Oligosaccharides: short chain of saccharide units
Why is the aldehyde carbon always found in position C1 in aldose sugars
The aldehyde carbon must be at the end of the chain since its double bonded to an oxygen and one hydrogen. The only other bond that is possible is to the rest of the carbons in the chain
What is the property of glucose that changes the specific rotation when dissolved in water and what is a specific rotation
Mutarotation is when a sample of the alpha or beta anomer of glucose is dissolved in water.
Specific rotation is the angle through which the plane of polarization changes when a plane of polarized light is passed through a sample
