Carbohydrates Flashcards
What is the most abundant biomolecule on earth
sugars
What is an example of a part of the body that relies ONLY on sugar for energy
the brain
Sugars are essential components of….. (think DNA and RNA)
nucleic acids
Differentiate between mono, di, oligo, and polysaccharides
mono=1
di=2
oligo=3-19 (short)
poly=20 or more (long)
What is an important chemical property of monosaccharides
very water soluble (opposite to lipids)
What is the formula for monosaccharides
(CH2O)n
What two chemical functional groups are required in the structure of monosaccharides
carbonyl (aldehyde or ketone)
hydroxyl groups (at least 2)
Draw the structure of glyceraldehyde (aldose) and dihydroxyacetone (ketose)
on slide 43 of second half lectures 1-4
What is the simplest class of monosaccharides
triodes (3 carbons)
What class of monosaccharides are the most common in nature
hexoses
Much of our understanding of carb chemistry goes back to what scientist
Emil Fischer
What does it mean to be an enantiomer
mirror image of one another
What is identical between enantiomers
chemical properties
What is different between enantiomers
optical activity
What are diastereomers
when handedness at some carbons differ and some do not
What is different about diastereomers
chemical properties and optical activity
How do you identify between D and L sugars
D sugars is if the chiral carbon atom furthest away from the carbonyl has the same configuration as D-glyceraldehyde
L sugars is if the configuration resembles L-glyceraldehyde
Most (but not all) naturally occurring sugars are what configuration (D or L)
D
What are epimers
when the sugars are identical at all carbons except for one
special case of diastereomers
What is the formula to determine the number of stereoisomers in a sugar
2^n (where n is the number of chiral carbons)
- half of the stereoisomers will be D and half will be L
What is the relationship between every time a carbon is added and number of isomers
every 1 carbon that’s added, isomers double
Aldehyde + alcohol =
hemiacetal
Ketone + alcohol =
hemiketal
The hemiacetal and hemiketal formations turn sugars into….
rings
What is the term for when hemiacetal and hemiketals turn sugars into rings
cyclization of sugars
What is the term for ring-structured sugars that only differ at the anomeric carbon
anomers
What is an example of anomers
a-glucose and b-glucose
When dissolved in water, glucose converts into an equal distribution of alpha, beta, and linear forms; what is this process called
mutarotation
In mutarotation, what is the effect on optical properties
they are identical
What is a pyranose
a 6-C ring
What is a furanose
a 5-C ring
If the OH is above in the Haworth formation, glucose is….
beta (left in Fischer formula)
If the OH is below in the Haworth formation, glucose is….
alpha (right in Fischer formula)
The carbonyl carbon is always the ______________ in the cyclization reaction
electrophile
If a sugar turned from blue to red with the addition of cuprous ion (Cu2+) what does this mean
reducing sugar
What does it mean to be a reducing sugar
reacts with oxidants
What is a glycoside
condensation of the anomeric carbon (acting as electrophile) has occurred with nucleophilic OH or NH creating a molecule called a glycoside
What is a glycosidic bond
when the anomeric carbon reacts with the OH of an alcohol
What is a glycosilic bond
when the anomeric carbon reacts with the NH group of an amine
If the anomeric carbon is involved in a glycosidic bond, the sugar becomes a…
non-reducing sugar
why: because the sugar can no longer open up to assume its linear form (only open chain forms of sugar can undergo oxidation)
How are dissacharides formed
two monosaccharides are linked through a glycosidic bond
Are disaccharides glycosides?
yes
How are disaccharides named in terms of their glycosidic bond
anomeric carbon is in either alpha or beta configuration, reacting with the hydroxyl group on a certain carbon of the other sugar
for example; the glycosidic bond of lactose is between beta anomeric carbon 1, and the hydroxyl group on carbon 4: would be called (b1-4)
If one anomeric carbon is still free to undergo mutarotation in a disaccharide, is this molecule a reducing or nonreducing sugar
reducing (the end not involved in the glycosidic bond is known as the reducing end)
What is a double headed sugar
when both anomeric carbons are used in the glycosidic bond (non reducing)
Polysaccharides are often highly ______________
branched
What are homopolysaccharides
made from a single type of sugar unit
What are heteropolysaccharides
made from two or more kinds of sugar subunit
What are glucans
glucose homopolymers
What are mannans
mannose homopolymers
