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Chemical composition of cells, molish test, benedict test, 2.1.5.1biuret -…
Chemical composition of cells
Proteins
building blocks
:organic compound,
amino acids
Protein is formed when
amino acids are bound together by a peptide bond
, which formed from the attachment of the carboxyl group of the first amino acid to the amine group of the second amino acid, after removing a water molecule, (condensation)
Test of the
presence of peptide
bond
Biuret
test
:check:Positive result:
Violet
colour
:green_cross: Negative results:
Blue
colour
Proteins function
: It do most of the
work in cells
and are required for the
structure
,
function
, and
regulation
of the body’s tissues and organs.
Carbohydrates
Forms:1-
Monomers
(Ex:
Glucose
, fructose, galactose) 2-
Dimers
(Ex:
sucrose
, lactose, maltose) 3-
Polymers
(Ex: glycogen, cellulose,
starch
)
Tests of the
presence of carbohydrates
Molisch
test: Detect any form of carbohydrates
( general)
:check:Positive result:
Red- or Purple
- colour
Benedict's
test: Detect the presence of
reducing sugars
(monosaccharides and some disaccharides) Ex: glucose, lactose, maltose
:check:Positive result:
Green to Red
colour
:green_cross:Negative result:
blue
colour
Iodine
test: Detects presence of polymer form (polysaccharide), Ex:
starch
:check:Positive result:
Dark blue
:green_cross:Negative result:
yellow to brown
colour
Polysaccharides properties
and
function
: 1- Long chain 2- complex sugar 3-Formed from
simple sugar
5- In plant (starch) & (cellulose) 4- In animals (glycogen) 6- Two types<
storage
: starch & glycogen /
structure
:cellulose & chitin> 7- Bonded through a glycosidic bond
Lipids
Lipids properties and function
: 1-
Store more energy
than carbohydrates 2- Important for the cell membrane 3-
Non polar
molecules 3-
Disperse in water only in presence of an emulsifier
4-
Not a polymer
5- Bonded through an
ester bond
6- Ex: Cholesterol - Triglyceride - Phospholipid - Free Fatty Acid
Tests of the presentence of lipids
Emulsification
test: using a
emulsifier
which contains
molecules with both polar and nonpolar ends
:check: Positive result : cause
fat to disperse
in water
:green_cross: Negative result:
fat did not disperse
in water
Sudan Red
test: using it because it is
fat soluble
and
not water soluble
:check: Positive result:
Sudan dissolve
:green_cross: Negative result:
Sudan did not dissolve
What is the Importance of the
chemical composition ?
Using different
chemicals
in this laboratory to
test the presence
of specific organic molecules
