BIO 111 Lecture 4-CARBOHYDRATES MU C.ppt

Detailed presentation about Carbohydrate in biological science

1. BIOMOLECULES AND
CELLS: BIO 111
Mr. Derrick Banda MSc, BSc

2. How to get hold of Mr Derrick Banda
•Office: Mulungushi University,Main Campus, SSET
Offices
•E-mail: [email protected] [email protected]

•Phone Number: [phone]
: [phone]

3. BIOMOLECULES- CARBOHYDRATES

4. Introduction to Biomolecules
•Chemicals or molecules present in the living organisms are known
as Biomolecules.
•The sum total of different types of biomolecules, compounds and
ions present in a cell is called as cellular pool.
•Biomolecules are compounds of carbon. Hence the chemistry of
living organisms is organized around carbon.
•Carbon is the most versatile and the most predominant element of
life.

5. BIOMOLECULES

6. BIOMOLECULES

7. CARBOHYDRATES
•Carbohydrates are biological molecules made of carbon, hydrogen, and
oxygen.
•Carbohydrates (or glycans as they are often called) include simple
sugars (or monosaccharides) and all larger molecules constructed of sugar
building blocks.
•Carbohydrates can be represented by the formula (CH
2O)
n, where n is the
number of carbon atoms in the molecule. In other words, the ratio of carbon
to hydrogen to oxygen is 1:2:1 in carbohydrate molecules.
•The term carbohydrate is derived from the French term hydrate de carbone
i.e. it is a hydrate of carbon or C
n
(H
2
O)
n
•Carbohydrates are the most abundant organic molecules in nature.

8. CARBOHYDRATES
•Carbohydrates can be found in almost all food sources.
•Rice, cereal, potatoes, fruits, pasta, vegetables, etc., have some kind
of carbohydrate in them.

9. CARBOHYDRATES
•Carbohydrates can be compounds that are as simple as a single glucose ring, to
strings of these rings as starch.
•The glucose rings arrangement determines what kind of carbohydrate we have.
Loaf of bread Bread crumbs Polysaccharide (Starch)
Disaccharide
Monosaccharide (Glucose)

10. CLASSES OF CARBOHYDRATES
•Carbohydrate chains come in different lengths, and biologically important
carbohydrates belong to three categories: monosaccharides, disaccharides
(oligosaccharides) , and polysaccharides. 

11. CLASSES OF CARBOHYDRATES
Monosaccharides
Disaccharides
Polysaccharides

12. MONOSACCHARIDES
•Monosaccharides (mono– = “one”; sacchar– = “sweet”). A
monosaccharide is a carbohydrate consisting of one sugar unit.
•Monosaccharides are carbohydrate molecules that
cannot be broken down by hydrolysis into
simpler (smaller) carbohydrate molecules
•Monosaccharides are at times referred to as “simple sugars” or
just :sugars," which infers that they are the simplest (smallest)
of the carbohydrates.

13. MONOSACCHARIDES
•Glucose, galactose and fructose monosaccharides are
referred to as hexoses since they have six carbons.

14. MONOSACCHARIDES
•Common examples of simple sugars or monosaccharides are glucose,
galactose and fructose.
• Glucose is abundant in many plant sources and makes up sweeteners
such as corn sugar or grape sugar. While fructose is found in honey
and fruits. Galactose is called “milk sugar”

15. MONOSACCHARIDES
•Glucose and fructose are structural isomers of one another, with the
difference being that glucose contains an aldehyde functional group
(R-CHO) whereas fructose contains a ketone functional group
(RC(=O)R’).

16. MONOSACCHARIDES
•Glucose is a group of carbohydrates which is a simple sugar with a
chemical formula C
2H
12O
6. 
•It exists in two forms viz open-chain (acyclic) form or ring
(cyclic) form.

17. MONOSACCHARIDES
•Glucose exists in two forms viz open-chain (acyclic) form or
ring (cyclic) form.
•In aqueous (watery) solutions, monosaccharides form ring
structures

18. MONOSACCHARIDES
•We classify monosaccharide by the number of carbon atoms and the
types of functional groups present in the sugar.

19. MONOSACCHARIDES
•We classify monosaccharides by the number of carbon atoms and
the types of functional groups present in the sugar.
1.Sugars containing three carbons are known as trioses, those with
four carbons as tetroses, those with five carbons as pentoses,
those with six carbons as hexoses, and those with seven carbons
as heptoses.
2.If the sugar has an aldehyde group (the functional group with the
structure R-CHO), it is known as an aldose, and if it has a ketone
group (the functional group with the structure RC(=O)R’), it is
known as a ketose. 

20. MONOSACCHARIDES
•Ketose and aldose are monosaccharides which can be differentiated based
on the group they contain.
•An aldose is a monosaccharide whose carbon skeleton has an aldehyde
group. They are primarily found in plants.
•Ketose is a monosaccharide whose carbon skeleton has a ketone group..
Aldose Ketose

21. DISACCHARIDES
•Disaccharides are formed when two monosaccharides are chemically
bonded together. It involves the removal of a water molecule
(condensation).
•A covalent bond formed between two monosaccharides is known as
a glycosidic bond.
•Glycosidic bonds can be of the alpha or the beta type.

22. DISACCHARIDES
•Common disaccharides include lactose, maltose, and sucrose
Lactose is a disaccharide consisting of the monomers
glucose and galactose. It is found naturally in milk.
Maltose, or malt sugar, is a disaccharide formed by a
dehydration reaction between two glucose molecules.
The most common disaccharide is sucrose, or table sugar,
which is composed of the monomers glucose and fructose.

23. SYNTHESIS OF GLYCOSIDIC BOND
•During this process, the hydroxyl group of one monosaccharide
combines with the hydrogen of another monosaccharide, releasing a
molecule of water and forming a covalent bond.
•A covalent bond formed between two monosaccharides is known as
a glycosidic bond. Glycosidic bonds can be of the alpha or the beta type.
Remove OH
Remove
H
H
2O Forms

24. SYNTHESIS OF GLYCOSIDIC BOND
•Sucrose is formed when glucose and fructose are joined in a dehydration
reaction to form a glycosidic bond. In the process, a water molecule is lost.
•A covalent bond formed between two monosaccharides is known as
a glycosidic bond. Glycosidic bonds can be of the alpha or the beta type.
Remove OH
Remove H
H
2O Forms

25. DISACCHARIDES
•The maltose that flavours a malted milkshake (and other items) is
also a disaccharide made of two glucose molecules bonded together

26. DISACCHARIDES
•Sucrose, a common plant disaccharide is composed of the
monosaccharides glucose and fructose.
•Lactose, milk sugar, is a disaccharide composed of glucose and the
monosaccharide galactose.

27. HYDROLYSIS OF GLYCOSIDIC BOND
•Cells break down macromolecules by a process called hydrolysis (adding a
molecule of water)
•Water is added to split a double sugar

28. OLIGOSACCHARIDES
•Oligosaccharides are carbohydrates that contain between 3 and
10 single sugar residues.
•Common oligosaccharides include raffinose, stachyose, and
verbascose.
•These oligosaccharides can be found in relatively abundant levels
in legumes, whole grains, some cruciferous vegetables, and some
fruits.

29. OLIGOSACCHARIDES (RAFFINOSE)
•Most of the few naturally occurring oligosaccharides are found in
plants. 
•Raffinose, a trisaccharide found in many plants, consists of
galactose, glucose and fructose.

30. OLIGOSACCHARIDES
•Maltotriose is an oligosaccharide, a digestible carbohydrate,
composed of 3 glucose molecules linked with alpha-1,4
glycosidic bonds.

31. POLYSACCHARIDE
•Polysaccharides is a long chain of monosaccharides linked by
glycosidic bonds is known as a polysaccharide (poly– = “many”).
•The chain may be branched or unbranched.
•Polysaccharides may contain different types of monosaccharides.
•Starch, glycogen, cellulose, and chitin are primary examples of
polysaccharides.

32. STARCH
•A common plant polysaccharide is starch,
which is made up of many glucoses.
•Two forms of polysaccharide, amylose and
amylopectin makeup what we commonly
call starch.
•The formation of the ester bond by
condensation (the removal of water from a
molecule) allows the linking of
monosaccharides into disaccharides and
polysaccharides.
•Glycogen is an animal storage product that
accumulates in the vertebrate liver.

33. STARCH
•Starch is the stored form of sugars in plants and is made up of a
mixture of amylose and amylopectin (both polymers of glucose).
Starch is made up of glucose monomers that are joined by   1-4
α
or   1-6 glycosidic bonds.
α
•Plants are able to synthesize glucose, and the excess glucose, beyond
the plant’s immediate energy needs, is stored as starch in different
plant parts, including roots and seeds.
•The starch in the seeds provides food for the embryo as it germinates
and can also act as a source of food for humans and animals. The
starch that is consumed by humans is broken down by enzymes, such
as salivary amylases, into smaller molecules, such as maltose and
glucose. The cells can then absorb the glucose.

34. STARCH (Amylose versus Amylopectin)
•Amylopectin is a branched polysaccharide (  1-6 linkages at the branch
α
points), whereas Amylose is starch formed by unbranched chains of
glucose monomers (only   1-4 linkages).
α
•The numbers 1-4 and 1-6 refer to the carbon number of the two residues
that have joined to form the bond.

35. GLYCOGEN
•Glycogen is the storage form of glucose in humans and other
vertebrates.
•Like starch, glycogen is a polymer of glucose monomers, and it is
even more highly branched than amylopectin.
•Glycogen molecules are larger than those of amylopectin (up to 100
000 glucose units) and contain even more branches.
•Glycogen is usually stored in liver and muscle cells. Whenever blood
glucose levels decrease, glycogen is broken down via hydrolysis to
release glucose monomers that cells can absorb and use.

36. GLYCOGEN
•Glycogen consists of linear stretches of glucose residues connected by -
α
1 4-glycosidic bonds, with branches that are attached through -1 6-
→ α →
glycosidic bonds.  Each linear stretch contains approximately 13 glucose
residues.
•Like starch, glycogen is a polymer of glucose monomers, and it is even
more highly branched than amylopectin.

37. CELLULOSE
•Cellulose is a polysaccharide found in plant cell walls.

38. CELLULOSE
•Cellulose is a polysaccharide found in plant cell walls.
•Cellulose forms the fibrous part of the plant cell wall. In terms of
human diets, cellulose is indigestible, and thus forms an important,
easily obtained part of dietary fiber.
•As compared to starch and glycogen, which are each made up of
mixtures of a and b glucoses, cellulose (and the animal structural
polysaccharide chitin) are made up of only b glucoses.
•The three-dimensional structure of these polysaccharides is thus
constrained into straight microfibrils by the uniform nature of the
glucoses, which resist the actions of enzymes (such as amylase) that
breakdown storage polysaccharides

39. CELLULOSE
•Cellulose is the most abundant natural biopolymer. The cell wall of
plants is mostly made of cellulose; this provides structural support to
the cell. Wood and paper are mostly cellulosic in nature.
•Cellulose is made up of glucose monomers that are linked by   1-4
β
glycosidic bonds

40. CELLULOSE
•Cellulose are made up of only b glucoses.
•The three-dimensional structure of these polysaccharides is thus
constrained into straight microfibrils by the uniform nature of the
glucoses, which resist the actions of enzymes (such as amylase) that
breakdown storage polysaccharides.

41. POLYSACCHARIDE
•Polysaccharides are large molecules composed of individual
monosaccharide units.
•A common plant polysaccharide is starch, which is made up of many
glucoses.
•Two forms of polysaccharide, amylose and amylopectin makeup what
we commonly call starch.
•The formation of the ester bond by condensation (the removal of
water from a molecule) allows the linking of monosaccharides into
disaccharides and polysaccharides.
•Glycogen is an animal storage product that accumulates in the
vertebrate liver.

42. FUNCTIONS OF CARBOHYDRATES
1.Carbohydrates are the main energy source for the body. Your
brain needs it to think, muscles need it to make ATP for muscle
contractions. As well, every cell in your body needs carbohydrates
to function.
2.Carbohydrates function in short-term energy storage (such as
sugar); as intermediate-term energy storage (starch for plants and
glycogen for animals).
3.Present as structural components in cells (cellulose in the 
cell walls of plants and many protists), and chitin in the
exoskeleton of insects and other arthropods.
4.Precursors for many organic compounds (fats, amino acids)
5.Present as glycoproteins and glycolipids in the cell memebrane and
functions such as cell growth and fertilization

43. END OF LECTURE
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