Carbohydrates Flashcards
carbohydrate is a polyhydroxy aldehyde, a polyhydroxy ketone, or a compound that yields ________ or ________ upon hydrolysis.
polyhydroxy aldehydes
polyhydroxy ketones
means “hydrate of carbon”
Carbohydrate
Carbohydrates mean
means “hydrate of carbon”
Carbohydrates contain
Carbon
Hydrogen
Oxygen
Carbohydrates comes from the____ word “________” which means sugar
Latin
Saccharum
Importance of carbohydrates
Source of energy
Storage form of energy
Precursors to many organic compounds
Participates in the structure of cell membrane and cellular functions
Used as drugs like antibiotics
Classification of Carbohydrates
MONOSACCHARIDES
OLIGOSACCHARIDES
POLYSACCHARIDES
are the simplest sugars
cannot be hydrolyzed further into smaller units
contains a single carbon chain
MONOSACCHARIDES
MONOSACCHARIDES have __ to __ carbon atoms
3 to 9
Monosaccharides that don’t end in -ose
2 trioses = glyceraldehyde & dihydroxyacetone
CLASSIFICATION of MONOSACCHARIDES
• On the basis of number of carbons they posses
• ALDOSE or KETOSE depending upon their functional group
A 6-carbon monosaccharide and has an aldehyde functional group is called
ALDOHEXOSE
A 5-carbon monosaccharide with a ketone functional group is called =
KETOPENTOSE
Carbonyl group
C=O
ALL terminal groups of glucose (molecular formula), always ends with an_______ (e.g. СН2ОН)
alcohol
second-to-the-last carbon) = called the
penultimate carbon
Monosaccharides are classified on the number of C atoms.
Trioses
Pentoses
Hexoses
T or P or H
Glyceraldehyde
Trioses (C3H6O3)
M or P or S
Ribose
Pentose (C5H10O5)
M or P or S
Deoxyribose
Pentose (C5H10O4)
Pentoses C;H1o05
Examples
ribose, deoxyribose, ribulose
Trioses example
Glyseraldehyde
NADP
Nicotinamide
Adenine
Dinucleotide
Phosphate
FAD
Flavin
Adenine
Dinucleotide
HEXOSES
Examples
Glucose
Fructose
Galactose (CH12O6)
• Needed to synthesize:
Disaccharides
Polysaccharides
Hexose
CLASSIFICATION OF FUNCTIONAL GROUP IN MONOSACCHARIDES
Aldehyde
Keto
Aldehyde or Keto
Glucose
Aldehyde
Aldehyde or Keto
Fructose
Keto
STRUCTURE OF MONOSACCHARIDES
Fischer projection
Haworth projection
X-ray diffraction analysis
The straight chain structural formula
Fischer projection
Cyclic formula or ring structure
Haworth projection
Boat and chair form
X-ray diffraction analysis
Compounds possessing identical molecular formula but different structures =
isomers
Iso =
= “the same”
Types of Isomerism
Structural isomerism
Steroisomerism
Type of isomerism in which compounds have the same molecular formula but differ in positioning
Structural Isomerism
Type of Isomerism in which
• Differ in configuration
• Presence of Asymmetric carbon (chiral carbon) atoms
Stereoisomerism
4 types of Stereoisomerism
D and L isomerism
Optical isomerism
Epimerism
a and B anomerism
Chiral molecules that are mirror images of one another
Enantiomers
Has the -OH (hydroxyl) group on the
RIGHT of its PENULTIMATE carbon
D-Monosaccharide
• Has the -OH (hydroxyl) group on the
LEFT of its PENULTIMATE carbon
L-Monosaccharide
- second to the last carbon
PENULTIMATE CARBON
optically active compound is a compound that rotates the plane of polarized light.
Presence of asymmetrical carbon atom causes optical activity
OPTICAL ISOMERISM
When a beam of plane polarized light is passed through a solution of carbohydrate, it will rotate the light to the RIGHT
Dextro-rotatory
When a beam of plane polarized light is passed through a solution of carbohydrate, it will rotate the light to the LEFT
Laevo-rotatory
• The stereoisomerism if 2 monosaccharides differ from each other in their configuration around a single specific carbon (other than the anomeric) atom.
EPIMERISM
- carbon derived from the carbonyl carbon of the open-chain form of the carbohydrate molecule
ANOMERIC CARBON
• Isomers obtained from the change of position of hydroxyl group attached to the anomeric carbon
ANOMERISM
-OH group at the anomeric, carbon is on the SAME side as the terminal CH2OH
OH group = upward position
B (Beta)
OH group group at the anomeric carbon is on the side OPPOSITE from the terminal CH2OH
OH group = downward position
a (Alpha)
HAWORTH PROJECTION (2)
Pyran
Furan
• 6-membered hemiacetal ring
PYRAN
• 5-membered hemiketal ring
FURAN
MONOSACCHARIDES REACTION (2)
Oxidation to acidic sugars
Reduction to sugar alcohol
MONOSACCHARIDES REACTION (4)
- Weak oxidizing agent
- Strong oxidizing agent
- Enzymes
- Reduction
Oxidizing agent used determines product
• to produce acidic sugars
• To produce uronic acid
______ oxidizing agent
Present in Tollens and Benedict’s solution
Weak oxidizing agent
Weak oxidizing agent:
Oxidizes the aldehyde end of an aldose)to give an - _________
The oxidation of the aldehyde end of glucose produces - _________
The oxidation of the aldehyde end of galactose) produces - _________
aldonic acid
gluconic acid
galactonic acid
- is a carbohydrate that gives a positive test in Tollens and Benedict’s solution
Reducing sugar
Can oxidize both ends of the monosaccharide at the same time (carbonyl group & terminal primary alcohol group) to produce a dicarboxylic acid
Strong oxidizing agent
Can oxidize primary alcohol end of an aldose such as the D-glucose
Enzymes
Carbonyl group is reduced to a OH group using hydrogen as the reducing agent
Reduction to sugar alcohol
Reduction to sugar alcohol
Glucose turns to
Glucitol
Carbonyl group present in a monosaccharide (either aldose or ketose), can be reduced to a hydroxyl group using hydrogen as the reducing agent
Reduction
For aldoses and ketoses, the product of the reduction is the corresponding polyhydroxy alcohol which is commonly known as
sugar alcohol
In a reduction reaction
D-glucose becomes
D-glucitol
is an atom in a molecule that has four different groups tetrahedrally bonded to it.
chiral center
A molecule that contains a chiral center is said to be
chiral
molecule is a molecule whose mirror images are superimposable.
molecules do not possess handedness.
achiral
The simplest example of a chiral monosaccharide molecule is the three-carbon monosaccharide called
glyceraldehyde
are isomers that have the same molecular and structural formulas but differ in the orientation of atoms in space.
Stereoisomers
are stereoisomers whose molecules are nonsuperimposable mirror images of each other, as in left-handed and right-handed forms of a molecule.
Enantiomers
are stereoisomers whose molecules are not mirror images of each other.
Diastereomers
is a two-dimensional structural notation for showing the spatial arrangement of groups about chiral centers in molecules.
Fischer projection formula
is a compound that rotates the plane of polarized light.
optically active compound
enantiomer that rotates plane-polarized light in a clockwise direction (to the right) is said to be
dextrorotatory
is a chiral compound that rotates the plane of polarized light in a counterclockwise direction.
levorotatory compound
Although there is no limit to the number of carbon atoms that can be present in a monosaccharide, only monosaccharides with____ to ____ carbon atoms are commonly found in nature.
three to seven
Monosaccharides are classified as _____ or _____ on the basis of type of carbonyl group
aldoses or ketoses
is a two-dimensional structural notation that specifies the three-dimensional structure of a cyclic form of a monosaccharide.
Haworth projection formula