Slides contain carbohydrate, disaccharides, oligosaccharides, polysaccharides

1. CABRBOHYDRATES

2. • Carbohydrates are the most abundant biomolecules on Earth. Each year,
photosynthesis converts more than 100 billion metric tons of CO2 and H2O into
cellulose and other plant products.
• Certain carbohydrates (sugar and starch) are a dietary staple in most parts of the
world, and the oxidation of carbohydrates is the central energy-yielding pathway
in most non-photosynthetic cells.
• Carbohydrate polymers (also called glycans) serve as structural and protective
elements in the cell walls of bacteria and plants and in the connective tissues of
animals.
• Other carbohydrate polymers lubricate skeletal joints and participate in
recognition and adhesion between cells.
• Complex carbohydrate polymers covalently attached to proteins or lipids act as
signals that determine the intracellular destination or metabolic fate of these
hybrid molecules, called glycoconjugates.

3. • Carbohydrates are polyhydroxy aldehydes or ketones, or substances that yield
such compounds on hydrolysis.
•Many, but not all, carbohydrates have the empirical formula (CH2O)n; some also
contain nitrogen, phosphorus, or sulfur.
•First, carbohydrates serve as energy stores, fuels, and metabolic intermediates.
• Second, ribose and deoxyribose sugars form part of the structural framework of
RNA and DNA.
•Third, polysaccharides are structural elements in the cell walls of bacteria and
plants.
•Fourth, carbohydrates are linked to many proteins and lipids, where they play key
roles in mediating interactions among cells and interactions between cells and other
elements in the cellular environment.
• There are three major size classes of carbohydrates: monosaccharides,
oligosaccharides, and polysaccharides (the word “saccharide” is derived from the
Greek sakcharon, meaning “sugar”).

4. MONOSACCHARIDES
•Monosaccharides are colorless, crystalline solids that are freely soluble in water
but insoluble in nonpolar solvents. Most have a sweet taste.
•Monosaccharides, or simple sugars, consist of a single polyhydroxy aldehyde or
ketone unit. The most abundant monosaccharide in nature is the six-carbon sugar
D-glucose, sometimes referred to as dextrose.
•Monosaccharides of four or more carbons tend to have cyclic structures.
•Monosaccharides, the simplest carbohydrates, are aldehydes or ketones that
have two or more hydroxyl groups; the empirical formula of many is (C-H2O)n,
literally a "carbon hydrate.“
• Monosaccharides are important fuel molecules as well as building blocks for
nucleic acids.
•The backbones of common monosaccharides are unbranched carbon chains in
which all the carbon atoms are linked by single bonds.
•In this open-chain form, one of the carbon atoms is double-bonded to an oxygen
atom to form a carbonyl group; each of the other carbon atoms has a hydroxyl
group.

5. •If the carbonyl group is at an end of the carbon chain (that is, in an aldehyde group)
the monosaccharide is an aldose; if the carbonyl group is at any other position (in a
ketone group) the monosaccharide is a ketose.
•The smallest monosaccharides, for which n = 3, are dihydroxyacetone and d and l-
glyceraldehyde.
•They are referred to as trioses (tri- for 3). Dihydroxyacetone is called a ketose because
it contains a keto group, whereas glyceraldehyde is called an aldose because it
contains an aldehyde group.
•Glyceraldehyde has a single asymmetric carbon and, thus, there are two
stereoisomers of this sugar. d-Glyceraldehyde and l-glyceraldehyde are enantiomers,
or mirror images of each other.

7. •Simple monosaccharides with four, five, six, and seven carbon atoms are called
tetroses, pentoses, hexoses, and heptoses, respectively. Because these molecules
have multiple asymmetric carbons, they exist as diastereoisomers, isomers that
are not mirror images of each other, as well as enantiomers.
•In regard to these monosaccharides, the symbols d and l designate the absolute
configuration of the asymmetric carbon farthest from the aldehyde or keto group.
Figure 11.2 shows the common d-aldose sugars. d-Ribose, the carbohydrate
component of RNA, is a five-carbon aldose. d-Glucose, d-mannose, and d-
galactose are abundant six-carbon aldoses.
•Note that d-glucose and d-mannose differ in configuration only at C-2. Sugars
differing in configuration at a single asymmetric center are called epimers. Thus,
dglucose and d-mannose are epimeric at C-2; d-glucose and d-galactose are
epimeric at C-4. Dihydroxyacetone is the simplest ketose.
•The stereochemical relation between d-ketoses containing as many as six carbon
atoms are shown in Figure 11.3. Note that ketoses have one fewer asymmetric
center than do aldoses with the same number of carbons. d-Fructose is the most
abundant ketohexose.

10. •There are aldoses and ketoses of each of these chain lengths: aldotetroses and
ketotetroses, aldopentoses and ketopentoses, and so on.
• The hexoses, which include the aldohexose D-glucose and the ketohexose D-fructose
are the most common monosaccharides in nature—the products of photosynthesis,
and key intermediates in the central energy-yielding reaction sequence in most
organisms.
•The aldopentoses D-ribose and 2-deoxy-D-ribose are components of nucleotides and
nucleic acids

11. MONOSACCHARIDES HAVE ASYMMETRIC CENTERS
•All the monosaccharides except dihydroxyacetone contain one or more asymmetric
(chiral) carbon atoms and thus occur in optically active isomeric forms.
•The simplest aldose, glyceraldehyde, contains one chiral center (the middle carbon
atom) and therefore has two different optical isomers, or enantiomers .
•In general, a molecule with n chiral centers can have 2n stereoisomers.
Glyceraldehyde has; the aldohexoses, with four chiral centers.
•The stereoisomers of monosaccharides of each carbon-chain length can be divided
into two groups that differ in the configuration about the chiral center most distant
from the carbonyl carbon.
•Those in which the configuration at this reference carbon is the same as that of D-
glyceraldehyde are designated D isomers, and those with the same configuration as L-
glyceraldehyde are L isomers

13. CYCLIC STRUCTURES
•For simplicity, we have thus far represented the structures of aldoses and ketoses as
straight-chain molecules .
• In fact, in aqueous solution, aldotetroses and all monosaccharides with five or more
carbon atoms in the backbone occur predominantly as cyclic (ring) structures in which
the carbonyl group has formed a covalent bond with the oxygen of a hydroxyl group
along the chain.
• The formation of these ring structures is the result of a general reaction between
alcohols and aldehydes or ketones to form derivatives called hemiacetals or
hemiketals.
•Two molecules of an alcohol can add to a carbonyl carbon; the product of the first
addition is a hemiacetal (for addition to an aldose) or a hemiketal (for addition to a
ketose).
•Isomeric forms of monosaccharides that differ only in their configuration about the
hemiacetal or hemiketal carbon atom are called anomers, and the carbonyl carbon
atom is called the anomeric carbon.

16. DIASACCHARIDES
•Disaccharides (such as maltose, lactose, and sucrose) consist of two monosaccharides
joined covalently by an O-glycosidic bond, which is formed when a hydroxyl group of
one sugar molecule, typically cyclic, reacts with the anomeric carbon of the other (Fig.
7–10).
• This reaction represents the formation of an acetal from a hemiacetal (such as
glucopyranose) and an alcohol (a hydroxyl group of the second sugar molecule) (Fig. 7–
5), and the resulting compound is called a glycoside.

19. •Glycosidic bonds are readily hydrolyzed by acid but resist cleavage by base.
Thus disaccharides can be hydrolyzed to yield their free monosaccharide
components by boiling with dilute acid.
• N-glycosyl bonds join the anomeric carbon of a sugar to a nitrogen atom in
glycoproteins (see Fig. 7–30) and nucleotides.

20. •The oxidation of a sugar by cupric ion (the reaction that defines a reducing sugar)
occurs only with the linear form, which exists in equilibrium with the cyclic form(s).
•When the anomeric carbon is involved in a glycosidic bond (that is, when the
compound is a full acetal or ketal, the easy interconversion of linear and cyclic forms
is prevented.
• Because the carbonyl carbon can be oxidized only when the sugar is in its linear
form, formation of a glycosidic bond renders a sugar nonreducing.
•In describing disaccharides or polysaccharides, the end of a chain with a free
anomeric carbon (one not involved in a glycosidic bond) is commonly called the
reducing end.
•The disaccharide maltose contains two D-glucose residues joined by a glycosidic
linkage between C-1 (the anomeric carbon) of one glucose residue and C-4 of the
other.
•Because the disaccharide retains a free anomeric carbon, maltose is a reducing
sugar. The configuration of the anomeric carbon atom in the glycosidic linkage is
alpha . The glucose residue with the free anomeric carbon is capable of existing in
alpha- and beta-pyranose forms.

22. •The disaccharide lactose (Fig. 7–11), which yields D-galactose and D-glucose on
hydrolysis, occurs naturally in milk.
•The anomeric carbon of the glucose residue is available for oxidation, and thus
lactose is a reducing disaccharide. Its abbreviated name is Gal(beta1- 4)Glc.
•Sucrose (table sugar) is a disaccharide of glucose and fructose. It is formed by plants
but not by animals.
•In contrast to maltose and lactose, sucrose contains no free anomeric carbon atom;
the anomeric carbons of both monosaccharide units are involved in the glycosidic
bond (Fig. 7–11).

24. •Sucrose is therefore a nonreducing sugar, and its stability toward oxidation makes it a
suitable molecule for the storage and transport of energy in plants.
•In the abbreviated nomenclature, a double-headed arrow connects the symbols
specifying the anomeric carbons and their configurations.

25. •For example, the abbreviated name of sucrose is either Glc(alpha 1 <-> 2beta )Fru or
Fru(beta 2 <-> 1alpha)Glc.
•Sucrose is a major intermediate product of photosynthesis; in many plants it is the
principal form in which sugar is transported from the leaves to other parts of the
plant body.
•Trehalose, Glc(alpha1<-> 1alpha)Glc (Fig. 7–11)—a disaccharide of D-glucose that,
like sucrose, is a nonreducing sugar—is a major constituent of the circulating fluid
(hemolymph) of insects, serving as an energy-storage compound.
•Trehalose is a nonreducing sugar commonly found in bacteria, fungi, yeast, insects,
and plants. Significant levels of trehalose in plants act as protectants against various
abiotic stresses, including heat, drought, high salinity, and UV rays.
•Trehalose is also used commercially as a sweetener.

26. OLIGOSACCHARIDES
#Disaccharides
#Trisaccharides: having 3 monomers
Example Is “Raffinose”
•Raffinose is a trisaccharide composed of galactose, glucose, and fructose. It can
be found in beans, cabbage, brussels sprouts, broccoli, asparagus,
other vegetables, and whole grains.
• Raffinose can be hydrolyzed to D-galactose and sucrose by the enzyme α-
galactosidase (α-GAL), an enzyme not found in the human digestive tract. α-GAL
also hydrolyzes other α-galactosides such as stachyose, verbascose,
and galactinol, if present.

27. •Raffinose may have a form of a white crystalline powder. It is odorless and has a
sweet taste approximately 10% that of sucrose.
•It is non-digestible in humans and other monogastric animals (poultry) who do
not possess the α-GAL enzyme to break down RFOs. These oligosaccharides pass
undigested through the stomach and small intestine. In the large intestine, they
are fermented by bacteria that do possess the α-GAL enzyme and make short-
chain fatty acids (SCFA)(acetic, propionic, butyric acids), as well as the flatulence
commonly associated with eating beans and other vegetables.
•Raffinose is also used in:
skin moisturizers and smoothers
prebiotics (it allegedly promotes growth of lactobacilli and
bifidobacteria)
Food or drinks additive

28. #Tetrasaccharides: having 4 monomers
Stachyose:
•The general formula of a tetrasaccharide is typically C24H42O21.
•Stachyose is a tetrasaccharide consisting of two α-D-galactose units, one α-D-
glucose unit, and one β-D-fructose unit sequentially linked as
gal(α1→6)gal(α1→6)glc(α1↔2β)fru. Together with related oligosaccharides such
as raffinose, Stachyose occurs naturally in numerous vegetables (e.g. green
beans, soybeans and other beans) and other plants.
•Stachyose is less sweet than sucrose, at about 28% on a weight basis. It is mainly
used as a bulk sweetener or for its functional oligosaccharide properties.
•Stachyose is not completely digestible by humans

30. #Pentasaccharide: having 5 monomers
Verbascose:
a crystalline sugar C30H56O26 obtained from
mullein root.
It is a pentasaccharide that is stachiose
which has an additional unit of alpha-D-
galactopyranose attached by a 16
glycosidic linkage to the terminal galactosyl
reidue.
Derived from stachyose.
Gal(a1-6)Gal(a1-6)Gal(a1-6)Glc(a1-2b)Fruf

31. POLYSACCHARIDES
•Also known as Glycans.
•Molecular weight >20,000
•Homopolysaccharides
Heteropolysaccharides
•polysaccharides generally do not have
defining molecular weights
•For polysaccharide synthesis there is no
template; rather, the program for
polysaccharide synthesis is intrinsic to
the enzymes that catalyze the
polymerization of the monomeric units,
and there is no specific stopping point in
the synthetic process; the products thus
vary in length.

32. HOMOPOLYSACCHARIDE
1. As storage: starch, glycogen
2. As structural element in exosceleton: cellulose, chitin
As storage: Both polysaccharides occur intracellularly as large clusters or granules.
Starch and glycogen molecules are heavily hydrated, because they have many
exposed hydroxyl groups available to hydrogen-bond with water.
Most plant cells have the ability to form starch, and starch storage is especially
abundant in tubers (underground stems), such as potatoes, and in seeds.
STARCH:
Starch contains two types of glucose polymer, amylose and amylopectin . Amylose
consists of long, unbranched chains of D-glucose residues connected by (a1->4)
linkages (as in maltose). Such chains vary in molecular weight from a few
thousand to more than a million. Amylopectin also has a high molecular weight
(up to 200 million) but unlike amylose is highly branched. The glycosidic
linkages joining successive glucose residues in amylopectin chains are (a1->4);
the branch points (occurring every 24 to 30 residues) are (a1->6) linkages.

34. GLYCOGEN:
•Glycogen is the main storage polysaccharide of animal cells.
•Like amylopectin, glycogen is a polymer of (a1->4)-linked subunits of glucose, with
(a1->6)-linked branches, but glycogen is more extensively branched (on average, every
8 to 12 residues) and more compact than starch.
•Glycogen is especially abundant in the liver, where it may constitute as much as 7% of
the wet weight; it is also present in skeletal muscle.
•In hepatocytes glycogen is found in large granules, which are themselves clusters of
smaller granules composed of single, highly branched glycogen molecules with an
average molecular weight of several million.
•Such glycogen granules also contain, in tightly bound form.
•Because each branch in glycogen ends with a nonreducing sugar unit, a glycogen
molecule with n branches has n+1 non-reducing ends, but only one reducing end.

35. •When glycogen is used as an energy source, glucose units are removed one at a
time from the non-reducing ends.
•Degradative enzymes that act only at non-reducing ends can work simultaneously
on the many branches, speeding the conversion of the polymer to
monosaccharides.

36. DEXTRAN:
•Dextrans are bacterial and yeast
polysaccharides made up of (a1->6)-linked
poly-D-glucose; all have (a1->3) branches,
and some also have (a1->2) or (a1->4)
branches.
•Dental plaque, formed by bacteria growing
on the surface of teeth, is rich in dextrans,
which are adhesive and allow the bacteria to
stick to teeth and to each other.
•Dextrans also provide a source of glucose for
bacterial metabolism. Synthetic dextrans are
used in several commercial products (for
example, Sephadex) that serve in the
fractionation of proteins by size-exclusion
chromatography
• The dextrans in these products are
chemically cross-linked to form insoluble
materials of various sizes.

38. As structural element:
Cellulose:
•Cellulose, a fibrous, tough, water-insoluble substance, is found in the cell walls of
plants, particularly in stalks, stems, trunks, and all the woody portions of the plant
body.
•Cellulose constitutes much of the mass of wood, and cotton is almost pure
cellulose. Like amylose, the cellulose molecule is a linear, unbranched
homopolysaccharide, consisting of 10,000 to 15,000 D-glucose units.
•But there is a very important difference: in cellulose the glucose residues have
the Beta configuration, whereas in amylose the glucose is in the alpha
configuration.

39. •The glucose residues in cellulose are linked by (b1->4) glycosidic bonds, in contrast to
the (a1->4) bonds of amylose. This difference causes individual molecules of cellulose
and amylose to fold differently in space, giving them very different macroscopic
structures and physical properties.
•The tough, fibrous nature of cellulose makes it useful in such commercial products as
cardboard and insulation material, and it is a major constituent of cotton and linen
fabrics. Cellulose is also the starting material for the commercial production of
cellophane and rayon.
•Glycogen and starch ingested in the diet are hydrolyzed by a-amylases and
glycosidases, enzymes in saliva and the intestine that break (a1->4) glycosidic bonds
between glucose units.

40. •Most vertebrate animals cannot use cellulose as a fuel source, because they lack an
enzyme to hydrolyze the (a1->4) linkages. Termites readily digest cellulose (and
therefore wood), but only because their intestinal tract harbors a symbiotic
microorganism, Trichonympha, that secretes cellulase, which hydrolyzes the (a1->4)
linkages .
•There is one important exception to the absence of cellulase in vertebrates:
ruminant animals such as cattle, sheep, and goats harbor symbiotic microorganisms
in the rumen (the first of their four stomach compartments) that can hydrolyze
cellulose, allowing the animal to degrade dietary cellulose from soft grasses, but not
from woody plants.
•Fermentation in the rumen yields acetate, propionate, and b-hydroxybutyrate,
which the animal uses to synthesize the sugars in milk.
•The annual production of biomass on Earth (accomplished primarily by
photosynthetic organisms) is the energetic equivalent of nearly a trillion barrels of
crude oil, when converted to ethanol by fermentation.

41. •A major fraction of photosynthetic biomass is the woody portion of plants and
trees, which consists of cellulose plus several other polymers derived from
carbohydrates that are not easily digestible, either chemically or biologically.
•Lignins, for example, make up some 30% of the mass of wood. Synthesized from
precursors that include phenylalanine and glucose, lignins are complex polymers
with covalent cross-links to cellulose that complicate the digestion of cellulose by
cellulase.
•If woody plants are to be used in the production of ethanol from biomass, better
means of digesting wood components will need to be found.

42. Chitin:
•Chitin is a linear homopolysaccharide composed of N-acetylglucosamine residues in (b1->4)
linkage. The only chemical difference from cellulose is the replacement of the hydroxyl group
at C-2 with an acetylated amino group.
•Chitin forms extended fibers similar to those of cellulose, and like cellulose cannot be
digested by vertebrates.
• Chitin is the principal component of the hard exoskeletons of nearly a million species of
arthropods—insects, lobsters, and crabs, for example— and is probably the second most
abundant polysaccharide, next to cellulose, in nature; an estimated 1 billion tons of chitin are
produced each year in the biosphere.

43. HETEROPOLYSACCHARIDES
•The rigid component of bacterial cell walls (peptidoglycan) is a heteropolymer of alternating
(b1->4)-linked N-acetylglucosamine and N-acetylmuramic acid residues.
•The linear polymers lie side by side in the cell wall, cross-linked by short peptides, the exact
structure of which depends on the bacterial species.
•The peptide cross-links weld the polysaccharide chains into a strong sheath (peptidoglycan)
that envelops the entire cell and prevents cellular swelling and lysis due to the osmotic entry of
water.

44. •The enzyme lysozyme kills bacteria by hydrolyzing the (b1->4) glycosidic bond between N-
acetylglucosamine and N-acetylmuramic acid; the enzyme is found in human tears, where it
is presumably a defense against bacterial infections of the eye, and is also produced by
certain bacterial viruses to ensure their release from the host bacterial cell, an essential step
of the viral infection cycle.
• Penicillin and related antibiotics kill bacteria by preventing synthesis of the crosslinks,
leaving the cell wall too weak to resist osmotic lysis .
•Certain marine red algae, including some of the seaweeds, have cell walls that contain
agar, a mixture of sulfated heteropolysaccharides made up of D-galactose and an L-
galactose derivative ether-linked between C-3 and C-6.
•Agar is a complex mixture of polysaccharides, all with the same backbone structure but
substituted to varying degrees with sulfate and pyruvate. Agarose (Mr 150,000) is the agar
component with the fewest charged groups (sulfates, pyruvates).
•Agarose gels are used as inert supports for the electrophoretic separation of nucleic acids,
an essential part of the DNA-sequencing process.
• Agar is also used to form a surface for the growth of bacterial colonies.
•Another commercial use of agar is for the capsules in which some vitamins and drugs are
packaged; the dried agar material dissolves readily in the stomach and is metabolically inert.

46. GLYCOSAMINOGLYCANS:
•The extracellular space in the tissues of multicellular animals is filled with a gel-like
material, the extracellular matrix (ECM), also called ground substance, which holds
the cells together and provides a porous pathway for the diffusion of nutrients and
oxygen to individual cells.
• The ECM that surrounds fibroblasts and other connective tissue cells is composed of
an interlocking meshwork of heteropolysaccharides and fibrous proteins such as
fibrillar collagens, elastins, and fibronectins.
• Basement membrane is a specialized ECM that underlies epithelial cells; it consists
of specialized collagens, laminins, and heteropolysaccharides. These
heteropolysaccharides, the glycosaminoglycans, are a family of linear polymers
composed of repeating disaccharide units (Fig. 7–22).

47. •They are unique to animals and bacteria and are not found in plants.
•Some glycosaminoglycans contain esterified sulfate groups.
•The combination of sulfate groups and the carboxylate groups of the uronic acid
residues gives glycosaminoglycans a very high density of negative charge.
•To minimize the repulsive forces among neighboring charged groups, these
molecules assume an extended conformation in solution, forming a rod like helix in
which the negatively charged carboxylate groups occur on alternate sides of the helix
(as shown for heparin).
•The extended rod form also provides maximum separation between the negatively
charged sulfate groups.
• The specific patterns of sulfated and nonsulfated sugar residues in
glycosaminoglycans provide for specific recognition by a variety of protein ligands
that bind electrostatically to these molecules.

48. •The sulfated glycosaminoglycans are attached to extracellular proteins to form
proteoglycans .

49. The glycosaminoglycan hyaluronan (hyaluronic acid) contains alternating residues of
D-glucuronic acid and N-acetylglucosamine
 With up to 50,000 repeats of the basic disaccharide unit, hyaluronan has a molecular
weight of several million; it forms clear, highly viscous solutions that serve as lubricants
in the synovial fluid of joints and give the vitreous humor of the vertebrate eye its
jellylike consistency (the Greek hyalos means “glass”; hyaluronan can have a glassy or
translucent appearance).
Hyaluronan is also a component of the extracellular matrix of cartilage and tendons,
to which it contributes tensile strength and elasticity as a result of its strong
noncovalent interactions with other components of the matrix.
Hyaluronidase, an enzyme secreted by some pathogenic bacteria, can hydrolyze the
glycosidic linkages of hyaluronan, rendering tissues more susceptible to bacterial
invasion.
 In many animal species, a similar enzyme in sperm hydrolyzes an outer
glycosaminoglycan coat around the ovum, allowing sperm penetration.
Other glycosaminoglycans differ from hyaluronan in three respects: they are generally
much shorter polymers, they are covalently linked to specific proteins (proteoglycans),
and one or both monomeric units differ from those of hyaluronan.

50. Chondroitin sulfate (Greek chondros, “cartilage”) contributes to the tensile strength of
cartilage, tendons, ligaments, and the walls of the aorta.
Dermatan sulfate (Greek derma, “skin”) contributes to the pliability of skin and is also
present in blood vessels and heart valves. In this polymer, many of the glucuronate residues
present in chondroitin sulfate are replaced by their 5-epimer, L-iduronate (IdoA).

51. Keratan sulfates (Greek keras, “horn”) have no uronic acid and their sulfate content is
variable.
They are present in cornea, cartilage, bone, and a variety of horny structures formed of
dead cells: horn, hair, hoofs, nails, and claws.
Heparan sulfate (Greek hepar ¯ , “liver”; it was originally isolated from dog liver) is produced
by all animal cells and contains variable arrangements of sulfated and nonsulfated sugars.
The sulfated segments of the chain allow it to interact with a large number of proteins,
including growth factors and ECM components, as well as various enzymes and factors present
in plasma.
Heparin is a fractionated form of heparan sulfate derived mostly from mast cells (a type of
leukocyte). Heparin is a therapeutic agent used to inhibit coagulation through its capacity to
bind the protease inhibitor antithrombin.

52. Heparin binding causes antithrombin to bind to and inhibit thrombin, a protease
essential to blood clotting.
The interaction is strongly electrostatic; heparin has the highest negative charge
density of any known biological macromolecule (Fig. 7–23). Purified heparin is
routinely added to blood samples obtained for clinical analysis, and to blood donated
for transfusion, to prevent clotting

56. Sources of Carbohydrates
#Simple sugars are found in the form of fructose in many fruits.
#Galactose is present in all dairy products.
#Lactose is abundantly found in milk and other dairy products.
#Maltose is present in cereal, beer, potatoes, processed cheese, pasta, etc.
#Sucrose is naturally obtained from sugar and honey containing small amounts of
vitamins and minerals.
#These simple sugars that consist of minerals and vitamins exist commonly in milk,
fruits, and vegetables. Many refined and other processed foods like white flour,
white rice, and sugar lack important nutrients and hence, they are labelled
“enriched.” It is quite healthy to use vitamins, carbohydrates and all other organic
nutrients in their normal forms.

57. Functions of Carbohydrates
#The main function of carbohydrates is to provide energy and food to the body
and to the nervous system.
#Carbohydrates are known as one of the basic component of food including
sugars, starch, and fibre which are abundantly found in grains, fruits, and milk
products.
#Carbohydrates are also known as starch, simple sugars, complex carbohydrates
and so on.
#It is also involved in fat metabolism and prevents ketosis.
#Inhibits the breakdown of proteins for energy as they are the primary source of
energy.
#An enzyme by name amylase assists in the breakdown of starch into glucose,
finally to produce energy for metabolism.