PHL 224 Biochemistry II
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Prepared by Lect. Ghada Fekry
PHL 224 Biochemistry II
Attendance Sheet
Week
1st
22d
3rd
4th
5th
6th
7th
8th
9th
10th
11th
12th
13th
14th
Date
25/01/2015
01/02/2015
08/02/2015
15/02/2015
22/02/2015
01/03/2015
09/03/2015
15/03/2015
22/03/2015
29/03/2015
05/04/2015
12/04/2015
19/04/2015
26/04/2015
05/04/1436
12/04/1436
19/04/1436
26/04/1436
03/05/1436
10/05/1436
17/05/1436
24/05/1436
02/06/1436
09/06/1436
16/06/1436
23/06/1436
20/06/1436
07/07/1436
Exp.
_
Marks
_ _
_
Glucose, fructose
Lactose, Sucrose, starch, potato
Cont. Sucrose, maltose
Lipid & buffer
Amino acid & protein
Amino acid & protein
Amino acid Revision
Total marks
𝟏𝟎
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Prepared by Lect. Ghada Fekry
PHL 224 Biochemistry II
One of the crossover fields of chemistry, sometimes called "biological chemistry", is the study of chemical
processes within and relating to living organisms.
We like biochemistry because we learn about things that are inside of us. We can relate to what happens when
we eat and how our bodies are constructed, you will need to understand the information in both biochemistry
and organic chemistry. Why? Because the movement of atoms in the bio-chem world follows the same rules you
will learn in o-chem.
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PHL 224 Biochemistry II
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PHL 224 Biochemistry II
Are aldehyde or free ketone derivatives of polyhydric alcohols.
Classification of Carbohydrate
Monosaccharaides: can't hydrolyzed into simpler. They may classified as:
 trioses, tetroses, pentoses, hexoses or heptoses depending on the number of carbon atoms.
 And aldoses (e.g glucose, galactose and mannose) or ketoses(e.g fructose) depending upon whether they have an
aldehyde or ketone group.
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PHL 224 Biochemistry II
1. Disaccharides: are condensation products of two monosaccharaide units. ex. Maltose, lactose and sucrose.
2. Oligosaccharides: are condensation products of three to ten monosaccharaide units.
3. Polysaccharides: are condensation products of more than ten monosaccharaide units ex. Starch, glycogen and dextrin
Reducing sugar is a carbohydrate possessing either a free aldehyde or free ketone functional group.
Glucose: is the most important biological carbohydrates, it is produced by plants during photosynthesis. Glucose is reducing sugar.
Its stored as Starch in plant and as Glycogen by animals.
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Disaccharide Sucrose is Not reducing sugar.
PHL 224 Biochemistry II
No.
Carbohydrate
Classified as
Found in
Glucose
*(Blood sugar or grape sugar)
Galactose
hexa – aldoses- Monosaccharide
Plant
hexa –aldoses- Monosaccharide
not normally found in nature, but is mostly
hydrolyzed from the disaccharide lactose
3.
Mannose
hexa - aldoses -Monosaccharide
Fruits, vegetables
4.
hexa - ketoses - Monosaccharide
Fruit , honey
5.
Fructose*(fruit sugar)
Maltose (glucose + glucose)
*(malt sugar)
Reducing Disaccharide
Barley, germinating grain
6.
Lactose (glucose + galactose)
Reducing Disaccharide
Milk
Sucrose(glucose + fructose)
Non-Reducing Disaccharide
Cane sugar,Beat sugar
Homo- Polysaccharide
Potatoes, Wheat, corn, rice
1.
2.
7.
8.
*(Table Sugar)
Starch -(C6H10O5)-n
*known as
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Prepared by Lect. Ghada Fekry
PHL 224 Biochemistry II
Digestion:
1- Salivary alpha- amylase(stop in stomach because high acidity)
2- Pancreatic amylase in small intestine( pH 7.1)
3-
Intestinal enzymes
Monosaccharide
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PHL 224 Biochemistry II
Disaccharide
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PHL 224 Biochemistry II
No. Test
Solubility:
1.
Compound + water
Observation
Inference
Soluble in cold water
Mono and/or disaccharides
Insoluble in cold water but form colloid in Polysaccharides present
hot water
Molisch test:
Principle: carbohydrates when treated with con.
derivatives which condense with alpha naphthol to
Violet/purple ring at the junction Sugar present.
of two liquids
Its sensitive but a non-specific test and is
form colored hexoses yield 5-hydroxy methyl
given by all types of carbohydrates, if the
furfurals
Oligosaccharides or Polysaccharides are
Procedure: Mix 2ml of sugar sample with 5 drops of
present they are first hydrolysed to
Molisch's Reagent in a test tube. Add gently through
monosaccharaides
the side by tilting the tube, about 2 ml of
dehydrated to give the test positive.
Sulphuric acid undergo dehydration to give furfural
2.
which
are
then
concentrated H2SO4 so as to form a bottom layer.
Benedict’s test:
Principle: carbohydrates with free aldehyde or
3.
ketone groups have the ability to reduce cupric ions
Cu2+ to cuprous which combine with OH ions to form
Green, yellow, orange or brick
red precipitate is observed
yellow cuprous hydroxide upon heating converted to
Reducing sugar
Present
Benedict's test is a semi-quantitative test.
The color of the precipitate gives a rough
estimate of reducing sugar present in the
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PHL 224 Biochemistry II
red cuprous oxide(Cu2O).
Copper(II)
sample.
Copper(I) oxide (Cu2O)
Green precipitate
0.5 gm%
Procedure: Take 5 ml of Benedict's qualitative
Yellow precipitate
1 gm%
reagent, add 8 drops of sugar solution. Boil over a
Orange precipitate
1.5 gm%
Brick red precipitate  2 gm%
flame for 2 minutes or place in boiling water bath for
3 minutes. Allow to cool.
Fehling’s test:
Principle: Reducing sugar reacts with Fehling's
Yellow or brick red precipitate
Reducing sugar
Present
reagent in alkaline medium where reduction of deep
blue solution of cupric(II) to red ppt of cuprous oxide
Used
(Cu2O). Copper(II)
reducing and non-reducing sugar
4.
Copper(I) oxide (Cu2O)
to
differentiate
between
Procedure: 2 ml of Fehling's solution A + 2ml of
Fehling's solution B + 2 ml of Sugar solution Boil.
Barfoed’s test
Principle: aldoses and ketoses can reduce cupric ions
5.
even in acidic conditions.
Copper(II)
This
test
Copper(I) oxide (Cu2O)
is
used
to
distinguish
reducing
monosaccharides from disaccharides by controlling
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Prepared by Lect. Ghada Fekry
Red Precipitate
Monosaccharide present
Positive test indicates presence of
reducing monosaccharide
On prolong heating disaccharides can
also give test positive so solution should
be boiled for 3 minutes only
PHL 224 Biochemistry II
pH and time of heating, monosaccharides react very
fast whereas disaccharides react very slowly.
Procedure: Sugar solution + Barfoed’s reagent (Cu
Acetate/Acetic acid), heat for 3 min. on boiling W.B
Scanty brick red precipitate
Seliwanoff's Test
Principle:
keto
hexoses
on
treatment
with
Rose Red Color
hydrochloric acid form 5-hydroxy methyl furfural
6.
which on condensation with resorcinol gives a cherry
red colored complex.
Procedure:Sugar solution+ few crystals of Resorcinol
+ Equal volume of conc. HCl and warm on W.B.
Keto - hexoses Sugar present
Positive test given by Keto-hexoses.
On
prolong
heating
aldoses
converted to Keto-hexoses and give
positive reaction
Bial's test:
Principle:the test reagent dehydrates pentoses to
form furfural.
7-
Furfural further react with orcinol and the iron
present in the test reagent to produce a bluish
product.
bluish product.
Procedure: 2 ml of sample solution is placed in a test All other colours indicate –Ve
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Specific for pentose
Hexoses generally react to form green,
red or brown products.
PHL 224 Biochemistry II
tube and 2 ml of Bial's reagent is added, solution is
heated gently in hot W.B
Osazone test
As under microscope:
Principle: A solution of reducing sugar when heated
with
phenyl
hydrazine,
charactreristic
yellow Glucosazone: Needle shaped crystals
crystalline compounds called osazone are formed.
galactosazone: Rhombic shaped crystals.
These crystals have definite crystalline structure, Maltosazone: Sun flower shaped crystals
Glucose, fructose and Maltos and
lactose.
preciptation time and melting point for different lactose: Powder puff/hedgehog shaped
reducing sugars.
crystals.
8.
Procedure:
1- Add 10 drops of glacial acetic acid to 5 ml of
sugar solution in test tube.
Glucose, fructose and mannose
produce the same osazone
2- Then add a knife point of phenyl hydrazine
Galactosazone crystals are formed
hydrochloride and double the amount of sodium
in 7 min. Maltosazone crystals are
acetate crystals.
formed in 10-15 min
3- Mix and warm a little to see that the solids are
dissolved.
4- Filter the solution, and keep the filtrate in a
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Prepared by Lect. Ghada Fekry
PHL 224 Biochemistry II
boiling W.B for 20 min.
5- Cool slowly in water bath not under the tap to
have better crystals.
6- Examine the crystal under microscope.
Hydrolysis of sucrose (Inversion test)
Principle: sucrose on hydrolysis with HCl is converted
to glucose and fructose.
the prescence of these two monoscharides can be
Perform Benedict's and Seliwanoff's tests.
confirmed by Benedict's and Seliwanoff's tests.
9.
Procedure: add 2 drops of HCl and 1 drop of thymol
Boiled portion gives +ve Benedict's
blue to 5 ml of sucrose solution.
and Seliwanoff's
The development of pink color indicates that the
solution is acidic.
Divide it in to two equal parts
Boil one portion for about one min., cool under tape
water. Neutralize both portions by adding 2% sodium
carbonate drop by drop. Formatison of blue color
indicates neutralization .
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PHL 224 Biochemistry II
potato turns black
Iodine test:
Principle: If iodine is added to an peeled potato then
it will turn black.
10.
Starch
Procedure: iodine is added to an peeled potato
Iodine/Potassium iodide test:
Blue-black complex
Principle: iodine forms a coordinate complex
Starch confirmed
between the helically coiled polysaccharide chain and
The color obtained depends on the length
iodine.
11.
of the unbranched or linear chain.
Procedure: Two ml of a sample solution is placed in a
Amylose
test tube. Two drops of iodine / potassium iodide
solution and one ml of water are added.
Amylopectin
a) Lugol's Iodine
b) Starch solution
b) Starch solution with iodine
Results: On the basis of above observations the given sample was found to be sugar.
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colour
linear chain
branched
deep blue
chain
purple
PHL 224 Biochemistry II
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PHL 224 Biochemistry II
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Prepared by Lect. Ghada Fekry