Biological Molecules Flashcards
What is the suffix that designates a carbohydrate?
-ose
What is the difference between oligosaccharide and polysaccharide?
oligosaccharide = neither simple nor complex carbs, usually containing 3-10 repeating monomers
polysaccharide = complex carbs, made of >10 monomers
What are the 2 classifications of open-chain or linear forms of monosaccharides?
aldoses and ketoses
What is the difference between a D (+) sugar and an L (-) sugar? (consider fisher projection structures)
D sugar: highest number chiral carbon -OH on right
L sugar: highest number chiral carbon -OH on left
The human body has enzymes that recognize ______ sugars.
a) D
b) L
a) D
TRUE or FALSE: D and L correspond to R and S.
FALSE –> no relation at all
Draw the D-glucose and L-glucose enantiomers. Pay attention to the bottom cross.
ye draw it bruh
List the following from highest to lowest priority group (when designating D or L):
carboxylic acid, alcohol, carbonyl
carboxylic acid > carbonyl > alcohol
hint: most oxidized is highest priority and least oxidized is lowest priority
What is the “bottom cross rule” in terms of designating D and L? When can this rule be applied?
bottom cross rule = the direction of OH on the bottom cross of the sugar (in a fisher projection) determines D or L (i.e. if OH on left, then L enantiomer)
*can only be applied if highest priority carbon is at the top of the fisher projection diagram
How do you determine if 2 sugar molecules are enantiomers?
OPPOSITE absolute configuration of ALL chiral carbons
How do you determine if 2 sugar molecules are diastereomers?
> /= 1 chiral carbons with OPPOSITE absolute configuration AND >/= 1 chiral carbons with SAME absolute configuration
How do you determine if 2 sugar molecules are epimers?
EXACTLY 1 chiral carbon with opposite absolute configuration AND >/= 1 chiral carbon with the SAME absolute configuration
What reagents need to be added to an aldehyde/ketone to form a hemiacetal/hemiketal?
alcohol (with desired functional (R) group) + acid
TRUE or FALSE: even if a carbonyl/hydroxy group is located on the same molecule as an aldehyde/ketone, an intramolecular nucleophile addiction cannot take place
FALSE –> intramolecular reaction can occur to yield cyclic hemiacetal/hemiketal
TRUE or FALSE: furanose (5 member ring) is more stable than pyranose (6 member ring)
FALSE –> pyranose (6 member ring) is more stable than furanose (5 member ring)
How do you identify the anomeric carbon in a cyclic structure?
anomeric carbon is the only carbon with 2 oxygen groups attached to it
What is the difference between the alpha and beta anomer of D-glucose (structurally)? Which one is the major anomer and which one is the minor anomer? Draw the structures.
alpha = minor = OH at C1 is TRANS to C2OH at C5
beta = major = OH at C1 is CIS to C2OH at C5
did you draw it lol (hint: change the configuration at C1 of glucose)
Why is the beta-anomer of D-glucose major in comparison to the alpha-anomer?
beta is more stable because all substituents are equatorial (less sterically hindered)
How is Haworth projection (for chair/planar conformation) related to Fisher projection?
OH groups pointing LEFT in Fisher go UP in Haworth
OH groups pointing RIGHT in Fisher go DOWN in Haworth
In the Haworth projection for sugars, which direction does the CH2OH on C5 point for D sugars? What about for L sugars?
D sugar: CH2OH on C5 points UP
L sugar: CH2OH on C5 points DOWN
Draw the D glucose fischer projection and the beta D glucose haworth projection.
now go check it
What reagents should be added to form an acetal/ketal from a hemiacetal/hemiketal?
alcohol (with new R group) and acid
hint: same as from acetaldehyde/ketone to hemiacetal/hemiketal
What reagents can be used to reduce a sugar?
Tollens’ reagent and Benedict’s reagent
What kind of linkage is yielded when forming disaccharides?
1,4-linkage (glycosidic)
