Carbohydrates- sugar molecules
CARBOHYDRATES:
-Along with proteins and fats, carbohydrates are
one of three main nutrients found in foods

Glucose, or blood sugarcarbohydrates into glucose
breaks
down
-main source of energy for your body's cells,
tissues, and organs
Monosaccharides (one sugar molecule)
-glucose-fructose
-galactose

Disaccharides(Two sugar molecule)
-Maltose
TYPES OF CARBOHYDRATES:
-Sucrose

-Lactose
Simple carbs
-digest rapidly, immediate enegy, low in fiber,/
nutrients.
-hungry sooner
-are fruits, milk

Oligosaccharides(two-ten sugar molecules)
-Raffinose
-Stachyose

Polysaccharides(ten or more Sugar
Molecules)
-cake, candy and other refined sugar which also
provide energy but lack of vitamins, minerals and
fiber.
-starch

-glycogen
Complex carbs
- Starch and fiber
-cellulose
-digest slowly
Sugar- as food, becomes energy once processed
by the body
-Slow and sustained release of energy
-high in fiber/ nutrients
-feel fuller, loner
Dietary Fiber- This cannot be broken down by
human digestive enzymes, making it an
indigestible component of food.
- provide Vitamins, minerals, and fiber.
-Food such as Breads, legumes, rice, pasta,
starchy vegetables, beans, whole grains, oats,
green vegies, and potatoes.
CARBOHYDRATES

-reserve amount of carbs is stored in liver, and
muscles in the form of GLYCOGEN
Refined Carbs
- are cereals, grains, fruit, pastries, and bread
and pastas.
-Glucose- simplest form of carbs and the instant
source of energy.
-1gram of carbs provides 4 calories.
-Broadly defined as polyhydroxy aldehydes, or
ketones and their derivatives or as substance
that yields one of these compounds
-composed of carbon, hydrogen, and oxygen.
Essentially hydrates of carbon and water and
have composition of (CH2O)n or H- C-OH
- Functional groups present include hydroxyl
groups
- -ose indicates sugar
BIOCHEMISTRY- is the study of the chemical
substances found in living organisms and the
chemical interactions of these substances with
each other
5. linked to lipids are structural components of
cell membranes.
6. linked to proteins function in a variety of cell–
cell and cell–molecule recognition processes.
classification of Carbohydrates
-A carbohydrate is a polyhydroxy aldehyde, a
polyhydroxy ketone,
- or a compound that yields polyhydroxy
aldehydes or polyhydroxy ketones upon
hydrolysis.
-glucose is a polyhydroxy aldehyde,
-carbohydrate fructose is a polyhydroxy ketone.
-it is a filed of new discoveries are made almost
daily about how cells manufacture the needed
for life and how the chemical reactions by
which life is maintained occur.
Occurrence and Functions of Carbohydrates

-Dietary intake of plant materials is the major
carbohydrate source for humans and animals

-average human diet should ideally be about
two-thirds carbohydrate by mass
Carbohydrates have the following functions in
humans:
1. oxidation provides energy.
2. storage, in the form of glycogen, provides a
short-term
energy reserve.
3. supply carbon atoms for the synthesis of
other biochemical substances (proteins, lipids,
and nucleic acids).
4. part of the structural framework of DNA and
RNA molecules.


monosaccharide is a carbohydrate that
contains a single polyhydroxy aldehyde or
polyhydroxy ketone unit.
disaccharide is a carbohydrate that contains
two monosaccharide units covalently
bonded to each other.
oligosaccharide is a carbohydrate that
contains three to ten monosaccharide units
covalently bonded to each other.
polysaccharide is a polymeric carbohydrate
that contains many monosaccharide units
covalently bonded to each other.
Mirror Images
-is the key to understanding molecular
handedness. All objects, including all molecules,
have mirror images.
-reflection of an object in a mirror
Objects can be divided into two classes on the
basis of their mirror images:
1. Superimposable mirror images are images
that coincide at all points when the images
are laid upon each other.
2. Nonsuperimposable mirror images are
images where not all points coincide when
the images are laid upon each other.
The Importance of Chirality
Chirality
What is the importance of the handedness that
is now under discussion?
-contains a carbon atom with four different
groups bonded to it in a tetrahedral orientation
possesses handedness.
➤ In human body chemistry, right-handed and
left-handed forms of a molecule often elicit
different responses within the body.
-handedness-generating carbon atom is called a
chiral center.
➤ Sometimes both forms are biologically
active, each form giving a different
response;
-chiral center is an atom in a molecule that has
four different groups bonded to it in a
tetrahedral orientation.
-molecule that contains a chiral center is said to
be chiral
- chiral molecule is a molecule whose mirror
images are not superimposable. have
handedness
-achiral molecule is a molecule whose mirror
images are superimposable. do not possess
handedness.
➤ sometimes both elicit the same response,
but one form’s response is many times
greater than that of the other; and
➤ sometimes only one of the two forms is
biochemically active.
Stereoisomerism: Enantiomers and
Diastereomers
-Stereoisomers are isomers that have the same
molecular and structural formulas but differ in
the orientation of atoms in space.
-two major structural features that generate
stereoisomerism:
(1) the presence of a chiral center in a molecule
(2) the presence of “structural rigidity” in a
molecule. Structural rigidity is caused by
restricted rotation about chemical bonds. It is
the basis for cis–trans isomerism, a
phenomenon found in some substituted
cycloalkanes and some alkenes.
Stereoisomers can be subdivided into two
types:


Enantiomers-whose molecules are
nonsuperimposable mirror images of each
other. Left- and right-handed forms of a
molecule with a single chiral center are
enantiomers.
Diastereomers- whose molecules are not
mirror images of each other. Cis–trans
isomers (of both the alkene and the
cycloalkane types) are diastereomers.
Designating Handedness Using Fischer
Projection Formulas
Properties of Enantiomers
-Constitutional isomers differ in most chemical
and physical properties
Example: isomers have diff boiling and melting
points.
-Diastereomers also differ in most chemical and
physical properties.
In contrast, nearly all the properties of a pair of
enantiomers are same ( boiling and melting
points)
-Enantiomers exhibit diff. properties in only 2
areas
1. interaction with plane-polarized light
2. Interaction with other chiral substances
Interaction of enantiomers with planepolarized light
➤ All light moves through space with a wave
motion.
➤ Ordinary light waves- that is, unpolarized
light waves- vibrate in all planes at right
angles to their direction of travel.
Designating Handedness Using Fischer
Projection Formulas
➤ Plane-polarized light waves, by contrast,
vibrate in only one plane at right angles to
their direction of travel.
➤ Ordinary light can be converted to planepolarized light by passing it through a
polarizer, an instrument with lenses or
filters containing special types of crystals.
➤ When plane-polarized light is passed
through a solution containing a single
enantiomer, the plane of the polarized light
is rotated counterclockwise (to the left) or
clockwise ( to the right), depending on the
enantiomer.
-The key difference between plane polarized
light and ordinary light is that the planepolarized light has its vibrations occurring
within them in a single plane, whereas the
ordinary light has vibrations occurring within
them at random angles without any plane.
➤ -A light wave that is vibrating in more than
one plane is referred to as unpolarized light.
➤ Light emitted by the sun, by a lamp in the
classroom, or by a candle flame is
unpolarized light. Such light waves are
created by electric charges that vibrate in a
variety of directions, thus creating an
electromagnetic wave that vibrates in a
variety of directions.
➤ This concept of unpolarized light is rather
difficult to visualize. In general, it is helpful
to picture unpolarized light as a wave that
has an average of half its vibrations in a
horizontal plane and half of its vibrations in
a vertical plane.

It is possible to transform unpolarized light
into polarized light. The process of
transforming unpolarized light into
polarized light is known as polarization
Dextrorotatory and Levorotatory
Compounds

optically active compound is a
compound that rotates the plane of
polarized light.

dextrorotatory compound is a chiral
compound that rotates the plane of
polarized light in a clockwise direction.

A levorotatory compound rotates the
plane of polarized light in a
counterclockwise direction.
Classification of Monosaccharides

Monosaccharides are classified as aldoses
or ketoses on the basis of type of carbonyl
group present.

aldose is a monosaccharide that contains
an aldehyde functional group. Aldoses are
polyhydroxy aldehydes.

ketose is a monosaccharide that contains a
ketone functional group. Ketoses are
polyhydroxy ketones.

Monosaccharides are often classified by
both their number of carbon atoms and
their functional group.
A six-carbon monosaccharide with an aldehyde
functional group is an aldohexose; a fivecarbon monosaccharide with a ketone
functional group is a ketopentose
Biochemically Important Monosaccharides
- six that are particularly important in the
functioning of the human body are the trioses
D-glyceraldehyde and dihydroxyacetone and
the D forms of glucose, galactose, fructose, and
ribose.
-Glucose and galactose are aldohexoses,
fructose is a ketohexose, and ribose is an
aldopentose.
Cyclic forms of other monosaccharides
-Intramolecular cyclic hemiacetal formation and
the equilibrium between forms associated with
it are not restricted to glucose,
- A cyclic monosaccharides containing six atom
ring is called PYRANOSE
-One containing a five-atom ring is called
Furanose bcos their ring strictures resemble in
the ethers pyran and Furan.
➤ Haworth Projection Formulas
➤ Walter Norman Haworth (1883-1950), the
developer of Haworth projection formulas,
was a British carbohydrate chemist.
➤ He helped determine the structures of the
cyclic forms of glucose.
➤ He was the first to synthesize vitamin C,
and was a corecipient of the 1937 Nobel
Prize in Chemistry.
➤ Oxidation of the aldehyde end of glucose
produces gluconic acid,
➤ end of galactose produces galactonic acid.
➤ Because aldoses act as reducing agents in
such reactions, they are called reducing
sugars.
➤ With Tollens solution, glucose reduces Ag+
ion to Ag, and with Benedict’s solution,
glucose reduces Cu2+ ion to Cu+ ion.
➤ A reducing sugar is a carbohydrate that
gives a positive test with Tollens and
Benedict’s solutions.
➤ ,ketoses are also reducing sugars.
➤ In this situation, the ketose undergoes a
structural rearrangement that produces
an aldose, and the aldose then reacts.
➤ Thus, all monosaccharides, both aldoses
and ketoses are reducing sugars.
➤ Strong oxidizing agents can oxidize both
ends of a monosaccharide (the carbonyl
group and the terminal primary alcohol
group) to produce a dicarboxylic acid.
➤ Such polyhydroxy dicarboxylic acids are
known as aldaric acids. For glucose, this
oxidation produces glucaric acid.
➤ Monosaccharide oxidation can yield three
different types of acidic sugars.
➤ oxidizing agent used determines the
product.
➤ Weak oxidizing agents, such as Tollens
and Benedict’s solutions, oxidize the
aldehyde end of an aldose to give an
aldonic acid.
➤ enzymes can oxidize the primary alcohol
end of an aldose such as glucose, without
oxidation of the aldehyde group, to
produce an alduronic acid.
➤ glucose, such an oxidation produces Dglucuronic acid
Disaccharides
-monosaccharide that has cyclic forms
(hemiacetal forms) can react with an alcohol to
form a glycoside (acetal).
-This same type of reaction can be used to
produce a disaccharide, a carbohydrate in
which two monosaccharides are bonded
together.
-In disaccharide formation, one of the
monosaccharide reactants functions as a
hemiacetal, and the other functions as an
alcohol.
-A glycosidic linkage is the bond in a
disaccharide resulting from the reaction
between the hemiacetal carbon atom -OH and
an -OH group on the other monosaccharide.
-It is always a carbon–oxygen–carbon bond in a
disaccharide.
MONOSACCHARIDES
LACTOSE

-both maltose and cellobiose, the
monosaccharide units present are identical—
two glucose units in each case. However, the
two monosaccharide units in a disaccharide
need not be identical.



D-glucose- An aldohexose, most abundant,
blood sugar
D-galactose- Aldohexose, differs
structurally, brain sugar
D-fructose- ketohexose, structurally
identical to glucose, fruit sugar
D- ribose- aldopentose, same structure with
glucose but Carbon-3 removed
-Lactose is made up of a β-D-galactose unit and
a D-glucose unit joined by a β(1 : 4) glycosidic
linkage.
- Lactose is the major sugar found in milk. This
accounts for its common name, milk sugar.
Enzymes in mammalian mammary glands take
glucose from the bloodstream and synthesize
lactose in a four-step process.
SUCROSE
-common table sugar, is the most abundant of
all disaccharides and occurs throughout the
plant kingdom.
-It is produced commercially from the juice of
sugar cane and sugar beets.
-Sugar cane contains up to 20% by mass
sucrose, and sugar beets contain up to 17% by
mass sucrose.
Maltose
-often called malt sugar, is produced whenever
the polysaccharide starch breaks down,
happens in plants when seeds germinate and in
human beings during starch digestion.
-found in malted milk. Malt (germinated barley
that has been baked and ground) contains
maltose; hence the name malt sugar.
CELLOBIOSE
-produced as an intermediate in the hydrolysis
of the polysaccharide cellulose
- contains two D-glucose monosaccharide units.
GLYCOGEN

Glycogen, like starch, is a
polysaccharide containing only glucose
units. It is the glucose storage
polysaccharide in humans and animals.
Its function is thus similar to that of
starch in plants, and it is sometimes
referred to as animal starch. Liver cells
and muscle cells are the storage sites
for glycogen in humans.

Glycogen has a structure similar to that
of amylopectin; all glycosidic linkages
are of the a type, and both (1 : 4) and (1
: 6) linkages are present.

Glycogen is an ideal storage form for
glucose. The large size of these macromolecules prevents them from diffusing
out of cells.

Also, conversion of glucose to glycogen
reduces osmotic pressure

. High concentrations of glycogen in a
cell sometimes precipitate or crystallize
into glycogen granules.
Structural Polysaccharides

A structural polysaccharide is a
polysaccharide that serves as a
structural element in plant cell walls
and animal exoskeletons
1. Cellulose, the structural component of plant
cell walls, is the most abundant naturally
occurring polysaccharide. The “woody”
portions of plants—stems, stalks, and
trunks—have particularly high
concentrations of this fibrous, waterinsoluble substance.
2. Chitin is the second most abundant
naturally occurring polysaccharide. Its
function is to give rigidity to the
exoskeletons of crabs, lobsters, shrimp,
insects, and other arthropods. It also has
been found in the cell walls of fungi.
materials) to prevent the blood from
clotting.
Dietary Considerations and Carbohydrates

A simple carbohydrate is a dietary
monosaccharide.Simple carbohydrates
are usually sweet to the taste and are
commonly referred to as sugars.

A complex carbohydrate is a dietary
polysaccharide. The main complex
carbohydrates are starch and cellulose,
substances not generally sweet to the
taste.

A natural sugar is a sugar naturally
present in whole foods. Milk and fresh
fruit are two important sources of
natural sugars.

A refined sugar is a sugar that has been
separated from its plant source. Sugar
beets and sugar cane are major sources
of refined sugars.
Acidic Polysaccharides
a disaccharide repeating unit in which one
of the disaccharide components is an
amino sugar and one or both disaccharide
components has a negative charge due to
a sulfate group or a carboxyl group
Heparin
➤ Heparin is a small highly sulfated
polysaccharide with only 15-90
disaccharide residues per chain.
➤ The monosaccharides present in
heparin’s disaccharide
➤ Both of these monosaccharide
derivatives contain two negatively
charged acidic groups.
Glycolipids and Glycoproteins: Cell
Recognition

➤ Heparin is a blood anticoagulant. It is
naturally present in mast cells and is
released at the site of tissue injury.
A glycolipid is a lipid molecule that has
one or more carbohydrate (or
carbohydrate derivative) units
covalently bonded to it.

➤ It prevents the formation of clots in the
blood and retards the growth of
existing clots within the blood.
Glycolipids called cerebrosides and
gangliosides occur extensively in brain
tissue

Glycoprotein is a protein molecule that
has one or more carbohydrate (or
carbohydrate derivative) units
covalently bonded to it.

Glycoproteins called immunoglobins are
key components of the body’s immune
system response to invading foreign
materials.
➤ It does not, however, break down clots
that have already formed.
➤ Pharmaceutical-grade heparin is applied
as an anticoagulant to the
interior/exterior surface of external
objects that come in contact with
blood(test tubes, kidney dialysis
machine surfaces, prosthetic implant