.............. ................

1. UNIT# 04
CARBOHYDRATES
Lecture # 04
Course Title: Biochemistry
Course Incharge: Dr. Monica Ghouri (PHARM-D)

2. Carbohydrates
Carbohydrates are polyhydroxy aldehydes or ketones, or substances that
yield such compounds on hydrolysis.
 The name carbohydrate which is signifies as hydrate of carbon.
 Most abundant bio-molecules on Earth.
 Photosynthesis converts more than 100 billion metric tons of CO2 and H2O
into cellulose and other plant products/ year.
 Sugar and starch are a dietary staple in most parts of the world
 The oxidation of carbohydrates is the central energy-yielding pathway in
most non-photosynthetic cells.
 Insoluble carbohydrate polymers serve as structural and protective elements
in the cell walls of bacteria and plants and in the connective tissues of
animals.
 Many, but not all, carbohydrates have the empirical formula (CH2O)n
 Some also contain nitrogen, phosphorus, or sulphur. Carbs includes sugars are
also called saccharides.(saccharides = sugar)

3. Foods high in carbohydrates
 Sweets
 Soft drinks
 Breads
 Beans, peas
 Cereals, Rice, maize, barley, wheat, corn
 apricot, dates, blueberry, banana, grapes, apple, orange, pineapple,
strawberry and watermelon etc
 macaroni, spaghetti, potato, carrot

4. Examples of Carbohydrates
 Glucose: major metabolic fuel of mammals
 Glycogen: storage; in animals
 Starch: Storage; in plants
 Cellulose: structure; in plants; in paper
 Chitin: stucture; in Arthropods
 Ribose: RNA, ATP, NAD
 Deoxyribose: DNA
 lactose: Milk

5. Functions
 Carbohydrates have six major functions within the body:
 Providing energy and regulation of blood glucose
 Sparing the use of proteins for energy
 Breakdown of fatty acids
 Biological recognition processes
 Flavor and Sweeteners
 Dietary fiber

6.  Carbohydrate is necessary for the regulation of nerve tissue and is the source of
energy for the brain.
 Some carbohydrates are high in fibre, which helps prevent constipation
 Structural components
 Carbohydrates are also important for the correct working of our brain, heart
and nervous, digestive and immune systems.
 Polysaccharides: storage of energy (e.g., starch and glycogen),
 structural components (e.g., cellulose in plants and chitin in arthropods).
 ribose in coenzymes (e.g., ATP, FAD, and NAD) and the backbone of RNA.
 Deoxyribose: component of DNA.

7. Structure of Carbohydrates (C (H2O) )
 Carbon-based organic compounds; hydrogen & oxygen present in the same
proportion as water.
 Mostly contain C,H, & O, in a ratio of 1:2:1, H double of O.
 A long chain or ring of carbon atoms with multiple hydrogen atoms or hydroxyl
groups (-OH) attached.

8. CLASSIFICATION
 Three major classes of carbohydrates:
 1. Monosaccharaides,
 2. Oligosaccharides, and
 3. Polysaccharides

9. 1. Monosaccharides
 (The word “saccharide” is derived from the Greek
sakcharon, meaning “sugar”).
 Monosaccharides, or simple sugars, consist of a
single polyhydroxy aldehyde or ketone unit.
 Depending upon the functional, Aldoses (CHO) or
Ketoses (C=O)
 The most abundant monosaccharide D-glucose,
sometimes referred to as dextrose.
Monosaccharides of more than four carbons tend
to have cyclic structures.
 Empirical formula (CH2O)n where n=3 or some
large number.

10. The monosaccrides are white crystalline solids, very soluble in water, most have sweet taste .

11. Oligosaccharides
 Oligosaccharides consist of short chains condensation products of two and ten of
monosaccharide units, or residues, joined by covalent linkages called glycosidic
bonds.
 E.g. most common sucrose, maltose and lactose.
 The most abundant are the disaccharides, with two monosaccharide units.e.g
maltose
 Typical is sucrose (cane sugar), which consists of the six-carbon sugars D-glucose and
D-fructose.
 All common monosaccharides and disaccharides have names ending with the suffix “-
ose.”
 In cells, most oligosaccharides consisting of three or more units do not occur as free
entities but are joined to non-sugar molecules (lipids or proteins) in glycoconjugates.

14. Polysaccharides
 Polysaccharides contain long monosaccharide units joined together by
glycosidic linkage.
 Most of them act as food storage for e.g. Starch. Starch is the main storage
polysaccharide for plants.
 It is a polymer of α glucose and consists of two components-Amylose and
Amylopectin.
 Cellulose is also one of the polysaccharides that are mostly found in plants.
 It is composed of β-D- glucose units joined by a glycosidic linkage between C1
of one glucose unit and C4 of the next glucose unit.

16. Classifications of polysaccharides
 Homopolysaccharides:
 A polysaccharide that contains the same type of monosaccharides is known as
a homopolysaccharide. Some of the important homopolysaccharides are:
 e.g; Glycogen, Cellulose, Starch, Inulin:
 Heteropolysaccharides:
 A polysaccharide that contains different types of monosaccharides is known as
a heteropolysaccharide. Some of the important heteropolysaccharides are:
 e.g; Hyaluronic acid, Heparin, chondroitin-4-sulfate, gamma globulin.

19. Biomedical Importance
 Most abundant dietary source of energy.
 Brain cells and RBCs are almost wholly dependent on carbohydrates as the
energy source. Also serve as storage form of energy –Glycogen.

 Carbohydrates are precursors for many organic compounds (fats, amino
acids).
 Participate in the structure of cell membrane & cellular functions (cell
growth, adhesion and fertilization).
 Certain carbohydrate derivatives are used as drugs, like cardiac glycosides /
antibiotics. (aminoglycosides, macrolides)
 DM (diabetes mellitus)