chapter 11 Flashcards
(104 cards)
what are carbohydrates?
aldehyde or ketone compounds with multiple hydroxyl groups
what are the 4 roles of carbs?
- energy stores, fuels, and metabolic intermediates
- ribose and deoxyribose sugars form part of the structural framework of RNAand dna
- polysaccharides are structural elements of cell walls of bacteria and plants
- linked to many proteins and lipds: help mediate interactions among cells and among other elements in the cellular environment
what are monosaccharides
the simplest carbohydrates: adehydes or ketones that have 2 or more hydroxyl groups
empiricle formula of monsacharides
C-(H2O)n (carbon hydrate)
what are the smallest monosaccharides called?
trioses
what are the 2 trioses?
hihydroxy acetone, and glyceraldehyde
how many steroismoers of dehydroxyacetone and glyceraldehyde are there?
no stereoisomer for dihydroxyacetone, 2 stereoisomers for glyceraldehyde due to 1 symmetric carbon
in fischer projections, which bonds come out of the page and which go into the page?
horizontal bonds (in front of the plane) vertical bonds (behind the plane)
what are monosaccharides called with 4, 5, 6, 7 carbon atoms?
tetroses, pentoses, hexoses, and heptoses
what do “L” and “D” designate in monosaccharides?
designate the absolution configuration of the asymmetric carbon farthest from the adehyde or keto group (D means OH on the right of the fischer projection)
are the D form and L form of the same sugar enantiomers?
yes they are mirror images
what are diastereomers?
not mirror immages of each other
what is it called if sugars differ in configuration at only 1 asymetric carbon?
epimers
how do you number a ketose?
start at end closest to carbonyl
why do sugars for rings?
aldehyde can react with an alcohol to form a hemiacetal
ketones can react with alcohol to form hemiketals
what do you call a 5 and 6 memvbered ring?
furanose, pyranose
substituents drawn to the right on a fisher projection are draw ________ on a haworth projection?
drawn down (down right rule)
for D sugars the higest number carbon is drawn _______ on a hawarth projection, how about for an L sugar?
drawn up for D
drawn down for L
how does OH group at anomeric position drawn for L and D
for D, alpha is down, and beta is up.
for L, alpha is up, and B is down
how does the prevalence of different forms of fructose change in different situations?
pyranose form predominates in fructose free in solution •! furanose form predominates in many fructose derivatives
what are the 2 non-planar conformations pyranose rings can adopt? which is more common for glucose?
chair and boat, chair
what non planar conformation are furanoses in?
puckered - 4 atoms nearly coplanar and 5th is .5 angstroms above the plane
what are the 2 conformations of ribose?
c2-endo (c2 is out of the plane on the same side as c5)
c3-endo (c3 is out of the plane on the same side as c5)
monosaccharides may react with alcohols and amines to form?
modified monosaccarides