THE MACROMOLECULES OF LIFE
Macromolecules are polymers (many units) ; molecules built from one or
a few kinds smaller molecules called monomers.
POLYMERS : Large molecules consisting of chains of repeating units.
Monomer
Polymer
MONOMERS: Building blocks of polymers
DEHYDRATION SYNTHESIS
n (monomer
)
enzyme
ATP
Polymer + (n-1) H2O
HYDROLYSIS
Polymer + (n-1)H2O
enzyme n
(monomer)
@
All polymers are built by the same chemical reaction called
dehydration (removing water) synthesis (putting together) in
which monomers are joined by covalent bonds. Wherever a
covalent bond develops between two monomers, a water
molecule forms and leaves the polymer.
HO- - H + OH - -Hmonomer monomer
HO - --- -H + H2Omonomer monomer
Covalent Bond
One of the monomers loses a hydroxyl group (OH) and
the other loses a hydrogen atom (H). The hydroxyl group
and the other hydrogen atom then combine to form water
The reverse reaction known as hydrolysis (water breakdown,
splitting)
breaks a polymer into its component monomers. A molecule of
water is added for each covalent bond that is broken. The water
molecule is split into its two components : the hydroxyl group
attaches to one monomer and the hydrogen atom attaches to the
other.HO - --- - H + H2Omonomer monomer
HO - - H + OH - - Hmonomer monomer
CARBOHYDRATES
ORGANIC COMPOUNDS
•They contain C, H, O and some contain N or S
•They are also called as sugars
•They have the same ratio of hydrogen to oxygen as water has. Carbohydrates contain two ‘H’ atom for each ‘O’ atom.
•Their simple formula is (CH2O)n
•Green plants are the primary producers of carbohydrates. They synthesize carbohydrates by photosynthesis.
-Structure and Function of Carbohydrates-
•Organisms use carbohydrates as energy source. •Certain carbohydrates are used as structural material for cell. Ex: cellulose
CLASSIFICATION OF CARBOHYDRATES
There are 3 types of carbohydrates
Monosaccharides
(Simple Sugars)
Disaccharides(Double Sugars)
Polysaccharides(Many Sugars)
Structural Polysaccharid
es
Functional Polysaccharid
es
Trioses
Pentoses
Hexoses
MONOSACCHARIDES
Pentoses (C5H10O5) ex: ribose deoxyribose ribulose
Trioses (C3H6O3)intermediate products in photosynthesis and cellular respiration ex: PGAL
Hexoses (C6H12O6) ex: glucose fructose galactose
Hexoses (C6H12O6)
• All hexoses have same molecular formula. The molecular formula is ‘C6H12O6’. Glucose, fructose and galactose have same molecular formula but the arrangement of the atoms are different in each molecule. We call these molecules isomers.
glucose fructose galactose
• They are the primary energy sources for all cells ! ! !
GLUCOSE :•also known as dextrose or grape sugar•its produced by green plants •nearly all organisms use glucose as basic energy•source.
FRUCTOSE : •is the sweetest sugar (fruit sugar)•found in ripe fruit, honey and nectar of flowers
GALACTOSE : is found in milk (milk sugar)
DISSACHARIDES
They are formed when two monosaccharides combine by eliminating a water molecule. This reaction is called dehydration synthesis.
C6H12O6 + C6H12O6 C12H22O11 + H2O
In dehydration synthesis, hydrogen (H+) is removed from one monosaccharide and hydroxide (OH-) is removed from the other and water is formed. The monosaccharides are bind together. The bond that joins two monosaccharides is called glucoside bond.
monosaccharideH
OHH
OH+ monosaccharide
HOH
H
OH
ATP, enzyme
monosaccharideH
OHH
O monosaccharideH H
OH+ H2O
In this type of reaction a water molecule is returned to the
place from which it was removed in dehydration synthesis.
O
glycoside bond
+ H2OOH
+OH
sucrose + water glucose + fructose (C12H22O11) (H2O) (C6H12O6) (C6H12O6)
The reverse of dehydration synthesis is hydrolysis, which is breaking down reaction.
DISACCHARIDES
•They are less soluble in water and less sweet. •They must be broken down first by hydrolysis reactions and then taken into cell.
X + Y
monosaccharides
ATP
Enzyme
Z
disaccharide
+ H2O
glucose + glucose maltose (malt sugar) + H2O
glucose + fructose sucrose (table sugar) + H2O
glucose + galactose lactose(milk sugar) + H2O
Three types of monosaccharides
glucose + galactose Lactose + water (C6H12O6) (C6H12O6) (C12H22O11) (H2O)
POLYSACCHARIDES• also known as multiple sugars
• are large molecules formed by dehydration synthesis of glucose molecules
n(glucose)
Enzyme ATP
polysaccharide + (n – 1) H2O
• they are less soluble in water and not sweet
• are large molecules formed by dehydration synthesis of glucose molecules
STARCH : is made up of glucose it is storage polysaccharide in plants potatoes, rice, bread and pasta are rich in starch ***The existence of starch is determined by lugol or iodine solution. Starch produces a dark-blue color with iodine.
GLYCOGEN :• animal starch• in humans, animals excess sugar is stored in liver and muscle• it is long chain of glucose• it is storage polysaccharide
CELLULOSE : • it supports the plant• it is found in cell wall• it is the major component of wood• it is found only in plants• it is composed of only glucose• it is structural polysaccharide in plants
CHITIN : • it is made up of mainly glucose and N• the shell of an insect• it is structural polysaccharide
IMPORTANCE OF CARBONHYDRATES
Structural Chitin and cellulose
Energy Source glucose
Functional heparin; prevents blood clotting in blood vessels
Storage starch, glycogen
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