The document provides an overview of carbohydrates, detailing their chemical structure, classification into monosaccharides, disaccharides, and polysaccharides, along with their functions in the body as a primary energy source. Carbohydrates, stemming from photosynthesis, are essential organic molecules found in many foods and include examples like glucose, sucrose, and starch. The document also discusses the importance of stereoisomerism in the structural variations of carbohydrates.

1. Carbohydrates
By Prof. Liwayway Memije-Cruz

2. Carbohydrates

3. Origin of Carbohydrates
 compounds containing C, H and O usually with the
empirical formula Cm(H2O)n.
 Polyhydroxy Aldehydes and Ketones composed of Carbon,
Hydrogen and Oxygen.
 the nomenclature including Mono-, Di-, Oligo- and Poly-
"Saccharide" is preferred over the now obsolete and too-
general term "carbohydrate", since the etymological origin
of the word "carbohydrate" is from the greek words
Carbo- for carbon and hydor- for water which indicates
that the carbohydrates are "hydrates" of carbon and have
the empirical formula Cm(H2O)n, which is not always
true. Instead "saccharide" is derived from the greek word
for "sugar" and hence is much more accurate as it does not
limit the definition to any empirical formula.

4. Functions of Carbohydrates
 Carbohydrates provide
energy for the body,
enabling metabolism,
thus preventing the
breakdown of protein
as an energy source.
 Carbohydrates are the
preferred source of fuel
for the brain, muscle
and other organs.

5. Carbohydrates means
hydrated carbons; examples
are glucose (C6 H12O6) and
ribose (C5H10O5). They
provide an easy and ready to
use source of food.

6.  Carbohydrates, together with lipids,
proteins and nucleic acids, are one of the
four major classes of biologically essential
organic molecules found in all living
organisms.
 Carbohydrates, all coming from the process
of photosynthesis, represent the major part
of organic substance on Earth, are the most
abundant organic components in the major
part of fruits, vegetables, legumes and cereal
grains, carry out many functions.

8. Chemical Structure of Carbohydrates

9. Structures of monosaccharides,
disaccharides and polysaccharides

10. Monosaccharides are commonly
referred to as simple sugars.
Examples are:
Glucose – blood sugar which is the
universal cellular fuel
Fructose – fruit sugar is converted to
glucose for used by body cells.
Galactose – dairy products
Ribose - form part of the structure of
nucleic acids.

11. Glucose, Fructose and Ribose
MONOSACCHARIDES

12.  Monosaccharides are simple sugars,
which possess a free ketone or
aldehyde group. Being the simplest of
sugars, they cannot be further
hydrolyzed. Their chemical formula is
CnH2nOn or Cn(H2O)n.
 Monosaccharides are classified into
trioses, tetroses, pentoses, etc., and as
ketoses or aldoses, depending on their
ketone or aldehyde group.

13. Sucrose, Lactose and Malt sugar
OLIGOSACCHARIDES

14.  “Oligo” meaning few, oligosaccharides are sugars
that break down into two to 10 molecules of
monosaccharides when hydrolyzed.
 An oligosaccharide that yields two
monosaccharide molecules on hydrolysis is a
disaccharide, while those that break down into
three or four monosaccharides are called
trisaccharides, tetrasaccharides, and so on.
Disaccharides have a chemical formula of Cn
(H2O) n-1 while trisaccharides and others are Cn
(H2O) n-2, etc.
 Oligosaccharide examples include sucrose,
maltose, lactose, raffinose, and stachyose.
Oligosaccharide

15. Disaccharides are referred to as double sugars.
Some of the important disaccharides in the diet
include:
Sucrose (glucose-fructose), which is cane
sugar.
Lactose (glucose-galactose) found in milk.
Maltose (glucose-glucose) malt sugar.
Disaccharides must be broken down (digested)
to monosaccharide to be absorbed from the
digestive tract in to the blood.

16. Starch and Glycogen
POLYSACCHARIDES

17. Polysaccharides
• Polysaccharides are polymers consisting of 20 to
107 monosaccharidic units; they differ each other
for the monosaccharides recurring in the
structure, for the length and the degree of
branching of chains or for the type of links
between units.
• Polysaccharides are defined as:
a. omopolysaccharides - contain only one
type of monosaccharide as starch, glycogen and
chitin;
b. eteropolysaccharides -contain two or
more different kinds (e.g. hyaluronic acid).

18.  Polysaccharide, which literally means
much sugar, is a polymer of linked
monosaccharides.
 Starch is the storage polysaccharide
formed by plants as starchy foods like
grains and root vegetables (potatoes and
carrots).
 Glycogen is found in animal tissues like
in the muscles and the liver.

19. Stereoisomerism,
Carbohydrates, such as fructose and glucose,
with the same molecular formulas but with
different structural arrangements and
properties (i.e., isomers) can be formed by
relatively simple variations of their spatial, or
geometric, called stereoisomerism, which
exists in all biological systems

20. Stereoisomerism

21. References
 http://www.tuscany-
diet.net/carbohydrates/classification-
functions/
 http://www.newhealthadvisor.com/Classifi
cation-of-Carbohydrates.html
 https://www.britannica.com/science/carbo
hydrate/Role-in-human-
nutrition#ref593913