CARBOHYDRATES Cn(H2O) 1:2:1 (1C: 2H: 1O)
** Look for functional groups: 1) Aldehydes 2) Ketones 3) Alcohols
I. Nomenclature AND Classification, Common names:
** Named based on:
Length of carbon chain
Functional groups present on sugar
Stereochemistry of sugar
What 3 things must a molecule have to be classified as carbohydrate?
o 1) 3-carbon backbone
o 2) Aldehyde OR ketone group
o 3) @ least 2 hydroxyl groups
Hydrates of carbon can be named according to # of carbons it contains
o Cn = # of carbon atoms w/ matching H2Os
Carbohydrate = sugars, monosaccharides, disaccharides, polysaccharides
Carbonyl carbon = MOST oxidized = ALWAYS have lowest possible #
MONOSACCHARIDES= single/simplest carbohydrate unit
o Aka = simple sugar
SAME kind of molecule
Simplest monosaccharides trioses
o Common names: triose (3 carbons), tetrose (4 carbons), pentose (5 carbons),
hexose (6 carbons)
o -ose = denotes sugar
Aldose = aldehyde sugar (aldehyde group = most oxidized functional
group)
Ketose = ketone sugar (ketone group = most oxidized functional group)
o Include:
Glucose
Fructose
Galactose
Ribose
Xylose
Disaccharides = 2 sugars bound together
Polysaccharides = long sugar chains for glucose storage (i.e. glycogen in animals, starch
in plants)
Absolute configuration:
o Describes spatial arrangement of atoms OR groups around chiral molecule
o Assign priority to substituents of chiral carbon
HIGHER the atomic # HIGHER priority
Orient the molecule with the LOWEST priority substituent in the back
CLOCKWISE = R
COUNTERCLOCKWISE = S
Basic structure of monosaccharide => GLYCERALDEHYDE
o Polyhydroxylated aldehyde = aldose aldehyde sugar
Simplest aldose (Aldotriose)
Cyclic structure:
o Monosaccharides can undergo INTRAmolecular rxns to form RING structure
o Cyclic rings = stable in solution and can form 2 types of rings:
1) 6-membered rings 6 carbons in ring = PYRANOSE
2) 5-membered rings 5 carbons in ring = FURANOSE
Glycosidic linkages:
o Covalent bonds B/W monosaccharides AND alcohols
o Aldehyde carbon participate in glycosidic linkages
Sugars acting as substituents via linkage => Glycosyl residues
o When alcohol is another monosaccharide, produces a disaccharide
Examples:
Sucrose
Lactose
Maltose
Cellobiose
o Linkage b/w C1 on 1st sugar AND C2 on 2nd sugar
=> 1,2 linkage
o Linkage b/w C1 on 1st sugar AND C4 on 2nd sugar
=> 1,4 linkage
o Linkage b/w C1 on 1st sugar AND C6 on 2nd sugar
=> 1,6 linkage
May also be classified as alpha OR beta:
o Hydroxyl group on C1 => oriented UP = Beta (Birds fly in sky)
o Hydroxyl group on C1 => oriented DOWN = Alpha (Fish swim in sea Down
under)
PREFIX:
o Deoxy = has a -H in place of -OH @ certain position
o D/L = absolute configuration = assigned based on chirality of carbon atom
furthest from carbonyl group
o α/β = Anomeric configuration
SUFFIX:
o ALL sugars end in -ose
FUNCTION: Role of carbohydrates and sugars
1) Energy source/energy means energy stores (glycogen)
o Main energy source = Glucose
o Production of fats which are also used as energy source
o Energy stores => triglycerides
o Where do we get our sugar molecules come from?
Produced by plants capture energy stored in light transforms energy
into chemical bonds w/in sugar molecule
In sun have nuclear rxns taking place and release energy that is stored in
EM waves that propagate through space and makes way to plants
Plants take CO2 and H2O and use energy stored in light to produce sugar
molecule + O2 (use in ETC in process of aerobic cellular respiration)
Ingest carbohydrates produced by plants break down carbohydrates into
individual monomer sugars (if not glucose molecule then transform into
glucose molecule)
If have too many glucose can be stored as glycogen
Energy produced in nuclear rxn is stored in chemical bonds w/in sugar
molecules ingest sugar molecules – take same energy from sun and
store in ATP molecules and use ATP to carry out processes
o But do NOT have as high concentration of energy per gram as lipids b/w do NOT
have as high concentration of C-H bonds
Carbohydrates are produced by plants ingested & broken down into individual
monomer sugars
2) Formation of structural framework of Nucleic Acids
=> DNA & RNA:
o ATP contains a ribose sugar
o RNA & DNA: Nucleic Acids
Store genetic information
RNA = Ribose: ribo-nucleic acid
o Ribo = ribose sugar = pentose sugar
o Sugar links nitrogenous base to
phosphate group
DNA = DEOXYribose deoxy-ribo-
nucleic acid
o 2nd C = NO hydroxyl group
o Deoxy = 2’H (vs. 2’-OH in RNA)
o Acid = phosphate group gives it acidity
3) Cell walls of bacteria => Structural elements
o Bacteria
= peptidoglycan OR murein
o Plants
= cellulose
o Animals
= chitin
4) Lipid AND Protein Modifications:
o Linked to many proteins AND lipids
Cell-cell communication AND interactions B/W cells and other elements in
cell environment
o Use sugar to modify lipids and proteins diversify the capabilities and functionality
of proteins and lipids by
Attaching sugar components onto macromolecules by combining sugars
and proteins or sugars and lipids increase capabilities of these
Ex: Tissue factor (coagulation cascade) is a glycoprotein that
interacts w/ other molecules = initiate formation of blood clot (intrinsic
pathway of coagulation cascade)
o Sugars make up components of cell walls
MODIFICATION OF CARBOHYDRATES:
Monosaccharides may be modified via addition of groups
2 modifications of sugars:
o 1) PHOSPHORYLATION of Sugars:
When cells uptake sugar molecules the 1st step in glucose metabolism is
to phosphorylate glucose
Whenever a system in nature contains charge means its energy =
HIGHER = LESS stable = MORE reactive
By phosphorylating glucose molecule G-6-P => INCREASE
reactivity of glucose molecule to be able to undergo further
processes
INCREASE polarity of glucose molecule
Phosphorylated glucose contains HIGHR charge = MORE polar
MORE likely to spontaneously leave the cell
o b/c around the cell have cell membrane that contains
nonpolar lipid molecules, so HIGHLY polar glucose-6-
phosphate CANNOT spontaneously leave the cell b/c it
cannot pass across nonpolar bilayer membrane
surrounding the cell
st
1 step of glucose metabolism modifying glucose by ADDING phosphate group
o PHOSPHORYLATION of glucose gives => Net (-) charge => becomes anion
o Do this for 2 reasons:
o 2) Glycosidation w/ Alcohols:
NUCLEOTIDES:
Building blocks and involved in cell’s use of energy
Made up of 3 components:
o 1) 5 carbon (pentose) sugar
o 2) Nitrogenous base
o 3) Phosphate group
EPIMERS vs. ANOMERS:
o Epimers
o Differ in absolute configuration @ only 1 C R or S
o Anomers
o Differ in configuration @ hemiacetal/acetal = anomeric C
Note: Conversion B/W anomers = MUTAROTATION
GLUCOSE
Carbon backbone = makes it organic
CARBOHYDRATES
POLAR molecules
Dissolve in polar solvents
like H2O
Form hydrogen bonds w/ H2O
molecules
HYDROOHILIC
o Mix w/ H2O
2 functional groups:
o 1) Aldehyde
o 2) Ketone
1) ALDEHYDE:
ALCOHOL =
o ANY organic compound in which hydroxyl functional group OH = bound to
saturated carbon atom
o ALL have suffix -ol
o Carbon
=> double bonded to oxygen
=> single bonded to hydrogen
o Formed by:
Oxidation of alcohols
2) KETONE:
Organic compound R1 and R2 can be variety of carbon containing
substituents
o Carbonyl “sandwiched” B/W 2 radical groups (R1 & R2)
Carbohydrates are polyhydroxy aldehydes OR polyhydroxy
ketones
Car being hydrated
o 3 girls = 3 atoms C, H, & O
OH my god! What a wet (H2O) carbohydrates = hydrophilic
o Car has 4 wheels
Carbohydrate = 4 calories/g amt. energy in 1 g of carbohydrate
Hose suffix -ose
o Used in mono OR dia – saccharides
CARBOHYDRATES Right hand finger trick:
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