What are carbohydrates?
Carbohydrates are found in a wide array of both healthy and unhealthy foods—bread, beans, milk, popcorn, potatoes, cookies, spaghetti, soft drinks, corn, and cherry pie. They also come in a variety of forms. The most common and abundant forms are sugars, fibers, and starches.
Foods high in carbohydrates are an important part of a healthy diet. Carbohydrates provide the body with glucose, which is converted to energy used to support bodily functions and physical activity. But carbohydrate quality is important; some types of carbohydrate-rich foods are better than others:
The healthiest sources of carbohydrates—unprocessed or minimally processed whole grains, vegetables, fruits and beans—promote good health by delivering vitamins, minerals, fiber, and a host of important phytonutrients.
Unhealthier sources of carbohydrates include white bread, pastries, sodas, and other highly processed or refined foods. These items contain easily digested carbohydrates that may contribute to weight gain, interfere with weight loss, and promote diabetes and heart disease.
The Healthy Eating Plate recommends filling most of your plate with healthy carbohydrates – with vegetables (except potatoes) and fruits taking up about half of your plate, and whole grains filling up about one fourth of your plate.
Try these tips for adding healthy carbohydrates to your diet:
1. Start the day with whole grains.
Try a hot cereal, like steel cut or old fashioned oats (not instant oatmeal), or a cold cereal that lists a whole grain first on the ingredient list and is low in sugar. A good rule of thumb: Choose a cereal that has at least 4 grams of fiber and less than 8 grams of sugar per serving.
2. Use whole grain breads for lunch or snacks.
Confused about how to find a whole-grain bread? Look for bread that lists as the first ingredient whole wheat, whole rye, or some other whole grain —and even better, one that is made with only whole grains, such as 100 percent whole wheat bread.
3. Also look beyond the bread aisle.
Whole wheat bread is often made with finely ground flour, and bread products are often high in sodium. Instead of bread, try a whole grain in salad form such as brown rice or quinoa.
4. Choose whole fruit instead of juice.
An orange has two times as much fiber and half as much sugar as a 12-ounce glass of orange juice.
5. Pass on potatoes, and instead bring on the beans.
Rather than fill up on potatoes – which have been found to promote weight gain – choose beans for an excellent source of slowly digested carbohydrates. Beans and other legumes such as chickpeas also provide a healthy dose of protein.
3. CARBOHYDRATE
CHEMISTRY
• Definition :Polyhydroxy aldehydes or ketones
• Empirical formula : (CH2O) n----Hydrates of carbon
• C2H4O2---ACETIC ACID---NOT CARBOHTRATE
• C3H6O3 ---LACTIC ACID ---NOT CARBOHTRATE
PHYSICAL PROPERTIES
• SWEET TASTE
• WATER SOLUBLE
• SMELL OF BURNT SUGAR ON BURNING
• CRYSTALLINE
4. CARBOHYDRATE
CHEMISTRY
FUNCTIONS
ENERGY –4KCAL/GM
PRECURSORS OF ORGANIC COMPOUNDS—FAT
,AMINO ACIDS
STORAGE FORM OF ENERGY –GLYCOGEN
STRUCTURAL COMPONENTS OF MEMBRANE
STRUCTURAL COMPONENTS OF
CELLULOSE,EXOSKELETON,CELL WALL OF MICRO-
ORGANISMS
INDUSTRIAL—PAPER, TEXTILE
5. • Classification of carbohydrate
They broadly classified into:
Monosaccharides, Disaccharides, Oligosaccharide,
Polysaccharide
6. I.Monosaccharides
Simplest group of carbohydrate and are often referred to as
simple sugars
Can’t be further hydrolysed
Monosaccharides are further divided into different categories
based
on the functional group and number of carbonatoms
BASED ON FUNCTIONAL GROUPS
• ALDOSES—
• KETOSES—
CHO e.g. Glyceraldehyde, Glucose
C=O e.g. Dihydroxyacetone, Fructose
Based on the number of carbon atom
Trioses(3C), Tetroses(4c), Pentoses(5c) Hexoses(6c) and
Heptoses(7c)
7. II. Oligosaccharides
Oligosaccharide contain 2-10 monosaccharide molecule
which are liberated on hydrolysis.
Based on number of monosaccharide they are further
subdivided into Disaccharides, Trisaccharides etc
III.Polysaccharides
Polysaccharides are polymers of
monosaccharide unit They have high molecular
weight(up to a million)
They are usually tasteless(non-sugars) and form colloids with
water Polysaccharides are two types homopolysaccharides
and heteropolysaccharides
8. ISOMERISM
compounds that have the same chemical
formula but different structures are called
isomers. e.g. fructose, glucose, mannose,
and galactose are isomers of each other
having formula C6H12O6
Structural isomerism
Stereoisomerism
10. STEREOISOMERISM
Same molecular formula and same structure but they differ in
spatial configuration.
asymmetric carbon atoms allow the formation of stereoisomerism.
Asymmetric carbon (Chiral carbon ) means four different groups
are attached to that carbon.
The possible stereoisomers depend on the number of
asymmetric carbons
The formula 2n where n is the number of asymmetric carbons
present in the molecule.
D and L
isomeris
m
Optical
isomeris
m
Epimeris
m
α and
βanomeris
m
11.
12. D AND LISOMERISM
D and L isomers are mirror images of each
other. The orientation of –H and –OH group on
the penultimate carbon atom(C5) determines
whether the sugar is D or L isomers.
13. OPTICAL ISOMERISM
Optical activity is the capacity of a substance to
rotate the plane of polarized light passing through it.
It is the characteristic feature of compounds with
asymmetric carbon atom
Clockwise
direction
• Dextrorotatory(d) or
(+)
Counterclockwi
se direction
• Levorotatory(l)or (-
)
15. EPIMERISM
Epimerism is the stereoisomerism if two monosaccharides
differ from each other in their configuration around a single
specific carbon(other than anomeric) atom.
16. ANOMERISM
The and cyclic forms of D-glucose are known
as anomer. They differ from each other in
configuration only around C1 known as anomeric
carbon (hemiacetal carbon)
e.g. and glucose, and fructose.
17.
18. • Mutarotaion is defined as the change in the
specific
optical rotation by the interconversion of α
and β forms of D glucose to an equilibrium
mixture.
MUTAROTATION
19.
20. Reactions of Monosaccharides
• Tauto-merization –shifting of carbon atom from one
carbon to another
• Glucose/fructose /mannose ---undergo tautomerization when
placed in alkaline medium to form enendiol (intermediate of
highly reducing agent )
• Benedict's test
• Sugar -alkaline medium enendiol
21. Sugars due to their free aldehyde or keto group reduce cupric ions into cuprous
ions and give red precipitate.
Sucrose is non reducing sugar due to absence of free aldehyde or keto group.
Starch is also a non reducing sugar due to insufficient number of
reducing groups.
Test for reducing sugars(Benedicts test)
22. EPIMERS
• Monosaccharides which differ in
configuration around one specific C-atom
are called epimers of one another
• C-2 epimers
• glucose and mannose
• C-4 epimers
• glucose and galactose
23. H C
H
O
C OH
HO C H
C OH
H
H C OH
CH2OH
D-GLUCOSE
H C
HO C
O
H
HO C H
C OH
H
H C OH
CH2OH
D-MANNOSE
CARBON- 2
EPIMERS
25. Assignment 2
Difference between cis and trans isomers in a tabular form,
reducing sugars examples
and flowchart for isomerism
26. MUTAROTATION
• Alpha ,beta have diffirent optical activity
• GLUCOSE CRYSTALLIZED FROM WATER & ALCOHOLALPHA D –
GLUCOSE(+112.2ο ))
• GLUCOSE CRYSTALLIZED FROM WATERABOVE 98ο PYRIDINEBETA
D GLUCOSE (+18.8 ο )
• In aqueous solution the beta form of D glucose is more stable & predominant
• Definition –change in the specific optical rotation representing the interconversion of
alpha & beta form of D glucose to specific equilibrium mixture.( 52.7% )
• Inter conversion is faster in alkaline form.
• equilibrium mixture-has 63% of beta form,36% of alpha form& 1% 0pen chain form.
27. MUTAROTATION OF FRUCTOSE
• PYRANOSE (SIX MEMBER RING ) FUNAROSE (FIVE
MEMBER RING )
• CHAIR & BOAT CONFIRMATION OF FRUCTOSE
BOAT CHAIR
(LESS STABLE ) (MORE STABLE )
AXIAL EQUATORIAL ARRANGEMENT
PARALLEL HEAVY GROUPS PERPENDICULAR HEAVY GROUPS
29. On reduction of aldehyde group of glucose , it
forms sorbitol.
l
In diabetes mellitus, sorbitol accumulates in
the ends causing early cataract.
Fructose on reduction can form both sorbitol
and mannitol.
Mannose can form mannitol.
Mannitol is an osmotic diuretic and used to
reduce intracranial tension.
Galactose can form galactitol or dulcitol and its
accumulation in the lens causes early
development of cataract in galactosemia
condition.
30.
31. . ROLE OF CARBOHYDRATES
• As a major energy source for living
organisms (glucose is a principal energy
source in animal and plants)
• As a means of transporting energy ( exp:
sucrose in plant tissues)
• As a structural material ( cellulose in plants,
chitin in insects, building blocks of
nucleotides).
• As a precursor for other biomolecules
(purine, pyrimide)
32. IMPORTANCE OF MONOSACCHARIDES:
GLUCOSE
THE STORAGE FORM OF GLUCOSE IN
HUMANSIS GLYCOGEN
IN PLANTS IT IS STORED MAINLY IN THE
FORM OF STARCH.
DIETARY SOURCES: FRUITS, VEGETABLES(IN
THE FORM OF STARCH), HONEY
33. BIOLOGICAL SIGNIFICANCE
BRAIN CELLS, RBCS AND THE GROWING
EMBRYO ONLY UTILIZE GLUCOSE AS A
SOURCE OF ENERGY.
ENERGY SOURCE FOR CELLS IN THE
BODY.
BUILDING BLOCK OF DISACCHARIDES
AND POLYSACHHARIDES
IT IS THE SUGAR PRESENT IN BLOOD
34. IMPORTANT MONOSACCHARIDES
GLUCOSE FRUCTOSE GALACTOSE
D-Glucose:
D-glucose (dextrose) is the primary fuel in living cells especially in brain
cells that have few or no mitochondria.
Cells such as eyeballs have limited oxygen supply and use large amount of
glucose to generate energy
Dietary sources include plant starch, and the
disaccharides lactose, maltose, and sucrose
35. GALACTOSE: IMPORTANCE AND BIOLOGICAL
SIGNIFICANCE
DIETARY SOURCE: DIARY PRODUCTS
LESS SWEET THAN GLUCOSE
USED IN THE SYNTHESIS OF MILK SUGARIN
MAMMARY GLANDS
IT IS A CONSTITUENT OF GLYCOLIPIDSAND
GLYCOPROTEINS
IT IS REQUIRED FOR THE DEVELOPMENT OF
BRAIN AND NERVOUS TISSUE IN INFANTS.
36. MANNOSE
IT DOES NOT OCCUR FREE IN NATURE
IN THE HUMAN BODY, IT IS FOUND AS
A CONSITUENT OF GLYCOPROTEINS
ITS REDUCTION PRODUCT THAT IS
MANNITOL IS IMPORTANT CLINICALLY IN
CEREBRAL EDEMA.
37. CARBOHYDRATE EFFECTON
BRAIN FUNCTION
41
•
•
When carbohydrate intake is high, comprising 70% to
80% of total kcal, the brain produces more serotonin.
When produced in excess, serotonin causes a carving
for carbohydrate and therefore increased consumption
of carbohydrate, which in turn stimulates the
production of yet more excess serotonin.
This make a person sleepy and sluggish.
38. SOME ASPECTS OF THE ROLE OF
CARBOHYDRATE
42
•
•
•
•
•
•
Protein Sparing Action of Carbohydrates
The Need for Carbohydrates for the Oxidation of
Fats
Carbohydrates as a Source of Energy for Muscular
Work Special Functions of Carbohydrates in Liver
Synthesis of Ribose from
Glucose Carbohydrate and
Dental Health
39. . ROLE OF CARBOHYDRATES
•
•
•
As a major energy source for living
organisms (glucose is a principal energy
source in animal and plants)
• As a means of transporting energy ( exp:
sucrose in plant tissues)
As a structural material ( cellulose in plants,
chitin in insects, building blocks of
nucleotides).
As a precursor for other biomolecules
(purine, pyrimide)
40. PROTEIN SPARING ACTION OF
CARBOHYDRATES
44
The body uses mainly carbohydrates as a source of energy when they
are adequately supplied in the diet, thus sparing protein for tissue
building, since meeting the energy needs of the body takes priority
over other functions like growth.
If the diet does not supply adequate calories, the dietary proteinis
oxidized as a source of energy. There is also breakdown of tissue
proteins to a greater extent.
This function of carbohydrates serving as a source of energy and
preventing dietary protein from being oxidized and preventing excess
tissue protein breakdown in calorie deficiency in called “protein sparing
action of carbohydrates”.
For example, the daily urinary N excretion of 135 mg in an adult rat
during fasting is reduced to 93 mg when 12 g of glucose is fed tothe rat.
Glucose has spared about 33% of the body protein broken down in the
fasted rate
41. THE NEED FOR CARBOHYDRATES FORTH
OXIDATION OF FATS
• IN THE OXIDATION OF FATS, THE ACETYL COA FORMED FROM THE OXIDATIO OF FATTY
ACIDS REACTS WITH OXALOACETIC ACID (FORMED FROM CARBOHYDRATE BREAKDOWN
PRODUCT – PYRUVIC ACID OR FORMED FROM THE ASPARTIC ACID) TO FORM CITRIC
ACID WHICH IS OXIDIZED THROUGH THE TCA CYCLE BACK TO
OXALOACETIC ACID THROUGH A SERIESOF REACTIONS.
• IFADEQUATE AMOUNTS OF OXALOACETIC ACID ARE NOT AVAILABLE, ACETYL
COA IS FORMED IN LARGEAMOUNTS FROM THE OXIDATION OF FATTY ACIDS A
PART OF IT IS CONVERTED INTO KETONE BODIES (ACETOACETIC ACID AND
HYDROXY BUTYRICACID) WHICH ACCUMULATE IN BLOOD AND TISSUES AND
PRODUCE KETOSIS.
45
42. CARBOHYDRATES AS A SOURCE OF ENERGYFOR
MUSCULAR WORK
46
•
Carbohydrates are the major source of energy for muscular
work. During muscular contraction glycogen is broken down
to lactic acid. The process is known as glycolysis.
• During the recovery period lactic acid is first oxidized to
pyruvic acid and then to acetyl CoA, which in turn is
oxidized throughTCA cycle to CO2and H2O thus producing
energy for muscular work.
• As a source of energy, carbohydrates are more important
during moderate or severe muscular exerction as in
athletics.
43. CARBOHYDRATE AND
DENTAL CARIES
• DIETARY CARBOHYDRATE IS IMPLICATED ASA MAJOR CAUSE OF DENTAL
CARIES, OR TOOTH DECAY.
• HIGH INTAKE OF DIETARY SUGARS MULTIPLICATION OF ORAL BACTERIA
PRODUCTION OF ACID LOW ORAL PH DEMINERALIZATION OF TEETH
DENTAL CARIES.
• CARBOHYDRATE AS GLYCOPROTEINS
• CARBOHYDRATES AREFOUND IN THE FORM OF POLYSACCHARIDE CHAINS
ATTACHED TO PROTEINS SUCHAS GLYCOPROTEINS.AS SUCH THEYARE
IMPORTANT CONSTITUENTS OF TISSUEANTIGENS (IN THE CELLMEMBRANE)
AND SECRETED PROTEINS.
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