Biochemistry Carbohydrates Flashcards
How can you quickly determine if a chiral carbon on a carbohydrate is either D or L?
If the OH on the pentultimate carbon is on the left then it’s an L.
If the OH on the pentultimate carbon is on the right then it’s a R.
No relation to +/ -
What are epimers?
Subclass of diastereomers where they’re only different at one chiral carbon.
What is the difference between pyranose and furanose?
Furanose is a 5 membered ring.
Pyranose is a 6 membered ring.
How can you differentiate between the alpha and beta anomer?
Alpha looks like a fish, so it’s pointing down.
Beta must therefore be pointing up.
What is mutorotation?
In the presence of acid, base, or water. The anomeric carbon can flip back and forth between the alpha and beta configurations.
Which is more favored? The alpha or beta anomeric carbon?
Beta anomer is favored. Equatorial positions are more favored than axial therefore the beta anomer is favored.
describe GLYCOSIDE FORMATION.
DEHYDRATION REACTION. Removal of water to form o glycosidic bonds.
Describe phosphorylation of Glucose.
Phophorous group is added to C6 which gives the glucose molecule a charge. This polarity makes sure the glucose molecule doesn’t leave the cell before glycolysis.
What are reducing sugars:
have a free aldehyde group on C1 which acts as a reducing agent.
Describe N Glycosidic with amine.
Glucose reacts with amines to form N glycosidic bonds instead of an O glycosidic bond.
Describe Maltose bonds
Alpha- D-glucose combines with alpha d glucose. Forms an alpha, 1-4, glycosidic linkage.
What is special about sucrose in terms of bonding.
Both anomeric carbons are linked together via alpha glycosidic bonds, therefore it is a NONreducing sugar.
Describe Lactose bonds
beta d galactose binds to alpha d glucose to form beta 1,4 linkage.
Describe Surcose bonds
alpha d glucose + beta d fructose. forms 1,2 alpha linkages.
Short cut for alpha and beta anomers.
The greek alpha looks like a fish therefore it is AWAY, trans, and AXIAL from the last carbon.
Therefore beta must be cis and equatorial.
