17 - CARBOHYDRATES Flashcards
functions of carbohydrates/where can you find them
most abundant organic compounds in the plant world
storehouses of chemical energy
components of supportive structures
they are everywhere in nature
also components of nucleic acids (DNA and RNA)
formula for sugars
dehydration of sucrose with sulfuric acid
formula of monosaccharides and some examples
(CH2O)n where n=3
glyceraldehyde (an aldose)
dihydroxyacetone (a ketose), an active ingredient in self tanning product
how do you figure out D or L nomenclature of sugars
look at the orientation of the OH group the furthest away from the aldehyde
D or L does not tell us about the rotation
dextrorotatory and levorotatory in a polarimeter
only applies to glyceraldehydes
+ = dextrorotatory
L = levorotatory
reminder on R or S notation
counterclockwise=S
clockwise=R
how can you distinguish between D(-) erythrose and D(-) threose using NaBH4 and a polarimeter?
those are the two tetroses
what are the four D-pentoses and how you can remember them?
structures of L-lyxose and D-ribose and their relationship
what are the 3 D-aldohexoses?
method: allose has all 4 hydroxyls on the right
at C2: hydroxyls alternate right left
at C3: the first two are right, next to left, and so on
C4: first four on the right, rest on the left
C5: all hydroxys are on the right
what are the C3-C6 ketoses
how does glucose form a cyclic hemiacetal
what is the evidence for the cyclic pyranose form of glucose
what are anomers
what are the two possible hemiacetal structures of glucose
roughly a 2:1 ratio of beta to alpha
how are the anomers of glucose separated
what is mutarotation
cyclic acetals reactions
