8-carbohydrates (midterm 2 cutoff) Flashcards
what is the general formula of carbohydrates
(CH2O)n
what are some other elements that can be found in carbohydrates
N S P
what are carbohydrates (definition)
polyhydroxy aldehydes or ketones
what are 4 roles of carbohydrates
- fuel source/storage
- structural compounds
- recognition/regulation of extracellular proteins
- nucleic acid structure
are monosaccharides water soluble
yes
are disaccharides water soluble
yes
are oligosaccharides water soluble
yes
are homopolysaccharides water soluble
no
are heterpolysaccharides water soluble
no
what are homopolysaccharides and heteropolysaccharides
polymers of one or more carbohydrate unit, large and insoluble
what are glycoconjugates
carbohydrates joined to other molecular classes
what are 4 examples of glycoconjugates
proteoglycans, glycoproteins, peptidoglycan, glycolipids
what is a monosaccharide
aldehyde or ketone with two or more hydroxyl groups
what kind of chain is in monosaccharides and how are they connected
ubranched chains connected by single bonds
what is the chirality of monosaccharides
multiple chiral carbons
what is an aldose
when C1 has a carbonyl
what is a ketose
when C2 has a carbonyl
how do you name monosaccharides
based on the number of carbon atoms
what does triose mean
3 Carbon atoms in the monosaccharide
what does hexose mean
6 Carbon atoms in the monosaccharide
what is those most common # of C in monosaccharides
hexose 6
where does numbering begin in monosaccharides
the carbon closest to the carbonyl
why is glucose called an aldohexose
it has double bond at c1 and 6 carbons
how many chiral centers do all monosaccharides (except for dihydroxyacetone) have
at least 1
For N chiral centers, how mant possible steroisomers are there
2^N
what are epimers
isomers that differ in configuration at one ONE chiral carbon
what classified monosaccharides as D or L
based on the configuration of the chiral carbon most distant from the carbonyl group
what are enantiomers
mirror reflection stereoisomers
in fishcer projection, whcih side will the OH be on (starting from the C furthest from the carbonyl) for it to be a D isomer
OH on the right
in fishcer projection, whcih side will the OH be on (starting from the C furthest from the carbonyl) for it to be a L isomer
OH on the left
which carbon on glucose determines whether its D or L
C5
what happens if there is more than 2 chiral centers adjusted in a molecule (so if you compare the OG molecule to the one with 2 changed chiral centers)
it is not an epimer or an enantiomer - its just a stereoisomer
how many epimers of D-glucose are also D monosaccharides
3 (you can change C2 C3 and C4)
with an aldose and ketose with the same amount of carbons, how do they compare with the amount of chiral centers
why
there is 1 less chiral center in the ketoses compared to the aldose equivalents (because the ketone at C2 removes one stereocenter)
what is a pyranose
6 membered ring
what is a furanose
5 membered ring
what is the carbonyl converted to when it becomes a cyclic structure
either hemiacetal (aldose) or hemiketal (ketose)
how do monosaccharides adopt cyclic conformation (what is the reaction)
intramolecular rxn, C5 OH groups acts as a nucleophile towards the C1 or C2 carbonyl
what is an anomeric carbon
the carbon that is now in chiral form due to the monosaccharide becoming cyclic (so either C1 in aldoses or C2 in ketoses)
what is the structure of a hemiacetal
when an alcohol and ether are attached to the same carbon
what is the structure of a hemiketal
alcohol and ether attached to the same carbon with 2 other carbons attached
what is the difference with a hemiketal and a hemiacetal
hemiacetal will have an extra H group, in hemiketal that H group would be a C
how does the cyclic and linear form compare with the amount of chiral centers
the cyclic has 1 more chiral center
what 2 molecules react to create the hemiacetal
C-5 hydroxyl reacts with C-1 aldehyde
which is the anomeric carbon in glucose
C1
which is the new chiral carbon in glucose
C1
when do you have alpha glucose
then the OH of C1 is on the opposite side of the ring relative to C6 (OH down), C6 up)
when do you have beta glucose
then the OH of C1 is on the same side of the ring relative to C6 (OH up, C6 up)
how can you interconvert alpha and beta forms
by reforming the hemiacetal (mutarotation)
how do you know if glucose in ring structure is L
C6 will be down
how do you know if glucose in ring structure is D
C6 will be up
where is C6 and OH in alpha-D-glucopyranose
C6 up (D) OH down (alpha)
where is C6 and OH in beta-D-glucopyranose
C6 up (D) OH up (beta, same side)
where is C6 and OH in alpha-L-glucopyranose
C6 down (L) OH up (alpha means opposite site)
which OH carbon determines whether its alpha or beta
the OH on C1
where is C6 and OH in beta-L-glucopyranose
C6 down (L) OH down (beta, same side)
which form of glucopyranose has C6 up OH down
alpha-D-glucopyranose
which form of glucopyranose has C6 down OH down
beta-L-glucopyranose
which form of glucopyranose has C6 up OH up
beta-D-glucopyranose
which form of glucopyranose has C6 down OH up
alpha-L-glucopyranose
what % is usually beta in glucopyranose (how much is in that form compared to to other forms)
66%
what % is usually alpha in glucopyranose (how much is in that form compared to to other forms)
33%
what % is usually linear in glucopyranose (how much is in that form compared to to other forms)
less than 1%
is interconversion between alpha and beta spontaneous
explain (2 things)
yes, it will slowly come to equilibrium with the linear form as an intermediate
what is the name of the cyclic 5 carbon monosaccharide
furanose
what is the name of the cyclic 6 carbon monosaccharide
pyranose
which cyclic form can aldoses with 5 or more carbons form
pyranose or furanose
is pyranose or furanose more stable and why
pyranose because its larger
if OH is down on the Haworth projection, will it be on the right or left side in a fischer projection
right
whats the best 2 step process to determine whether its beta/alpha and L/D
1- look at C6 (down=L up=D)
2-look at C1 (opposite to C6=alpha same as C6=beta)
if OH is up on the Haworth projection, will it be on the right or left side in a fischer projection
left
if found on the left of the fischer diagram, will the OH be on the top of bottom in Hayworth
top
if found on the right of the fischer diagram, will the OH be on the top of bottom in Hayworth
down
what is so special about the bonding patten in anomeric carbons
they are the only ones that are attached to 2 oxygens (OH and ether)
is bond breaking required to go between chair conformations of pyranose rings
no
is it most stable to have equatorial or axial position in the chair
equitorial
thinking about the cyclohexane chair model, why is the beta form more common than alpha
because alpha requires you to have some the OH and C6 pointing in opposite directions, so there will be at least 1 thing in the axial form (but beta can have all in equitorial which is more stable)
where does the ether come from in glucopyranose
the OH from C5
what attacks which carbon to make a furanose ring
OH from C5 attacks carbonyl from C2
what attacks which carbon to make a pyranose ring
OH from C5 attacks carbonyl from C1
what are aldonic acids
oxidation at C1
how do you name aldonic acids
“-onic acid”
what are uronic acids
oxidation of primary alcohol
how do you name uronic acids
“-uronic acid”
what are 2 types of oxidized sugars
aldonic and uronic acids
what is a type of reduced sugar
alditol
what is an alditol
reduction of carbonyl to alcohol
how do you name alditols
“-itol”
what are deoxy sugars
removal of OH from monosaccharide
what is an amino sugar
replacement of OH (usually at C2) in monosaccharide with NH2 / NH3+
how do you name aino sugars
“-amine”
how and where do amino sugars differ than a normal sugar
OH is replaced with NH2 NH3+ (usually at C2)
what often happens to the amino group in amino sugars
it is acetylated
is there a charge on acetylated amino sugars
no
is there a charge on amino sugars
yes
