carbohydrates Flashcards
Carbohydrates are
aldehyde or ketone compounds with multiple hydroxyl groups
carbohydrates serve as
energy stores, fuels, and metabolic intermediates
structural framework
of RNA and DNA
structural elements in cell walls
mediating interactions among
cells and cells and other elements
empirical formula of carbohydrate
(C-H2O)n literally a “carbon hydrate.
smallest monosaccharides
dihydroxyacetone(ketose) and d- and l-glyceraldehyde (aldose) n=3 trioses
enantiomers
mirror image molecules
stereoisomers, diastereoisomers
?
fischer projections
atoms joined to an asymmetric carbon atom by horizontal bonds in front
of the plane of the page, and those joined by vertical bonds are behind
d and l -
absolute configuration of asymetrical carbon farthest from keto or aldeyde grp
aldehyde
?
keto grp
?
epimers
sugars differing in configuration at a single asymmetric center are called epimers.
glucose and d-mannose are epimeric at C-2
ketoses have one fewer asymmetric center than aldoses do with the
same number of carbons. why?
?
hemiacetal
aldehyde + alcohol
(structure?)
hemiketal
ketone + alcohol
pyranose
C1 aldehyde open chain of glucose + C 5 hydroxyl = 6 carbon cyclic hemiacetal
pyranose because similar to pyran
furanose
C2 keto grp open chain ketohexose(fructose) + C5 hydroxyl grp = 5carbon cyclic hemiketal furanose, similar to furan.
c2 keto can also react with C6 hydroxyl grp
Haworth projections
carbon atoms in the ring are not explicitly shown
The approximate plane of the ring is perpendicular to
the plane of the paper
heavy line on the ring projecting toward the reader
