Carbohydrates Flashcards
Lecture 1
What is the general imperical formula of sugar
CH2O
I have 4 carbons how many H, and O will be present in the sugar?
C4H8O4
List 5 functions of sugars
1, Energy store
- Energy source
- Part of RNA/ DNA
- Structual elements of cells wall
- Enzymes
T/F sugars are classified based on # of sugar units
True
1 sugar unit -
monosaccharide
2 sugar units
disaccharide
3-10 sugar units =
oligosaccharide
10 + sugar units =
polysaccharide
classify glycogen and starch based on # of sugar units
polysaccharides
classify maltose based on # of sugar units
disaccharide
classify sucrose based on # of sugar units
dissaccharide
classify lactose based on # of sugar units
disaccahride
classify glucose based on # of sugar units
monosaccharide
classify fructose base on # of sugar units
monosaccharide
classify galactose based on # of sugar units
monosaccharide
classify mannose based on # of sugar units
monosaccharide
C3(H2O)3 or C3H6O3 label based on # of carbons
Triose
C4(H2O)4 or C4H8O4 label based on # of carbons
Tetrose
C5(H2O)5 or C5H10O label based on # of carbons
Pentose
C6(H2O)6 or C6H12O6 label based on # of carbons
Hexose
C7(H2O)7 or C7H14O7 label based on # of carbons
Heptose
What are the 2 possible functional groups on a sugar
aldehyde or ketone
Aldoses (e.g., glucose) have an ____ group at ____
Aldoses (e.g., glucose) have an aldehyde group at one end
Ketoses (e.g., fructose) have a____ usually at _____
Ketoses (e.g., fructose) have a keto group, usually at C2
What is an isomer?
Compounds with the same molecular formula
but different molecular structures
T/F isomers must contain a stereocenter?
False!
What is a stereoisomer?
Compounds with same molecular formula and the
same structural formula but differ in the spatial
arrangement of the atoms in the molecule
T/F stereoisomers must contain a stereocenter
true
What is an enantiomer?
Two stereoisomers that are nonsuperimposable
mirror images of one another
Are meso compounds active or inactive
inactive
What is a meso compound
Meso compound: Stereoisomers that are superimposable mirror images. They are optically inactive.
What is a diastereoisomer?
Two stereoisomers but not mirror images on
each other
T/F enantiomers have opposite configurations at all
stereocenters
true !
T/F diastereomers have opposite configurations at some but not all, stereocenters]
True!
What is an epimer
Diastereomers that differ in the configuration
around a single asymmetric C atom only
An optical isomer rotates to the right, what is it considered
right — dextrorotatory [designated as “+”]
An optical isomer rotates to the left. what is it considered
left — levorotatory [designated as “-”]
T/F: there is no relation between D or L form of
sugar with the dextrorotatory (+)or levorotatory (-)
optical rotation]
True
Which carbon do we look at to see if a sugar is d or l
the penultimate! So if 6 carbons, look at carbon 5
How do I tell if a sugar is D or L?
look at the penultimate carbon. If OH is on the right its a D and if the OH is on the left its an L
In regards to the number of carbons, which types of sugars will cyclize?
Pentoses and hexoses
what type of bond do we see in a cyclized sugar
hemiacetal
a hemiacetyl bond is due to the reaction between an _____ or _____ and an _____ group .
a hemiacetly bond is due to the reaction between an aldehyde or ketone and an OH group
glucose can form what 2 kinds of rings
furanose or puranose
describe furanose
5 member ring, bond between c1 and c4
describe pyranose
6 member ring, bond between c1 and c5
What 2 kind of cyclical structures can fructose make, how many carobons and where are the bonds ?
furanonse 5 member ring, bond between c2 and c5 and pyranose 6 member ring, bond between c3 and c6
what kind of bonds link sugars
glycosidic bonds
what kind of bonds are in cyclical structures
hemiacytal bonds
What happens at the c1 when cycalization occurs
a new symetric center is formed at c1
How can i tell if anomers are alpha or beta?
alpha = below the ring beta = above the ring
How do you know if a sugar is L or D when looking at a ring structure
if the CH20H aka carbon 6 is above the ring its a D, if its below the ring its an L
How you know if a sugar is alpha or beta when looking at a ring structure?
If the anomeric OH is above the ring its beta , if the OH is below the ring it is alpha.
what is an epimer
Epimers: different configuration in just one chiral carbon
Anomers are simply special types of epimers T/F
True
What are Anomers: different configuration in the chiral, anomericcarbon when the molecule is in the cyclic form
different configuration in the chiral, anomeric carbon when the molecule is in the cyclic form
the glycosidic bonds are between which 2 carbons
1, 4
Describe what makes up a glycosidic linkage
Bond formed between the OH group of anomeric
carbon of monosaccharide and the OH group of another
compound
What is a N glycosidic bond
Bond formed between the OH group of anomeric carbon
and the nitrogen of an amine
what 2 sugars make up lactose
glucose and galactose
what 2 sugars make up sucrose
glucose and fructose
what makes something a reducing sugar
A sugar is classified as a reducing sugar only if it has an openchain form with an ALDEHYDE group or a free (anomeric C).
