carbohydrate structure and function Flashcards
Hemiacetals are formed by combining an acetal group with what other functional group?
Alcohol
Characteristic of Pyranose
very stable and common in nature
What is a pyranose
Six-carbon, cyclic sugar.
Which conformation has the lowest energy
Chair conformation, so they prefer to be in this position.
which group of sugars don’t form chair conformation
Furanose
Im six carbons long BUT, form a 5 carbon ring. What I’m I?
A furanose
Comparing between Furanose and Pyranose, which is more stable in nature.
Pyranose because of its chair conformation which takes on a lower energy and stable position.
what allows Anomerization possible
Aldehyde is a planar function group; Hydroxide from carbon 6 or 5 can attach either side resulting in either Alpha or Beta ring
An anomer is a special type of which isomer?
Epimer
What is Mutarotation
Tendency of a cyclic glucose that was an alpha anomer to be hydrolyzed into a strain chain that will either become Beta anomer or back to its alpha conformation.
Define Lactone
Any six membered cyclic esters
Define Tautomerization
A ketose, a non reducing sugar, is converted to an enol then to an aldose, which is a reducing sugar.
True or False:
A Ketose is a reducing sugar
False
Hydroxyl groups commonly play which role in esterification reactions?
Nucleophile
what is a glycoside
A molecules that contains a bond between a functional group and one of the carbons of the sugar.
That bond is Called the glycosidic linkage.
The same kind of linkage also found between di- and polysaccharides.
What type of bond joins phosphate and glucose in β-D-glucose-6-phosphate?
Glycosidic
Phosphofructokinase-1 (PFK-1) catalyzes the transformation of fructose-6-phosphate to fructose-1,6- bisphosphate. What is the role of the 1- hydroxyl in the reaction?
Nucleophile
One Example of a nucleophilic attack
Phosphorylation
True or False: Cellulose and amylose are polysaccharide chains of glucose that only differ in the orientation of their glycosidic linkages.
True
Many adults are unable to digest lactose; a disaccharide of galactose and glucose. What characteristic of lactose must be the underlying cause?
beta (1-4) linkage
Amylose is a linear chain of which glycosidic bond
Alpha 1-4
Cellulose is a structural polysaccharide for plant cell wall
which type glycosidic bond does it contain.
Beta 1-4
Even though amylopectin and glycogen are both polysaccharides with branch points. what distinctifies them
Amylopectin branch points are far in between (every ~25 carbs)
Glycogen branch points are closer at (every ~10 carbs)
Aldonic acids are compounds that
Have been oxidized, and have acted as reducing agents.
Define Mutarotation
Interconversion between anomers of a compound
Tautomerization
The interconversion of bonds, to undergo keto-enol shift.
ex: A ketone converted to an aldose.
What is amylose used for
storage of glucose in plants.
beta- amylase
Cleaves amylose at the non-reducing end of the polymer to yield maltose exclusively.
Alpha-amylase
Cleaves amylose anywhere yielding short polysaccharides, maltose and glucose.
These molecules are cyclic forms of Ketose and aldoses respectively
Hemiketal and Hemiacetal
