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LICEO SCIENTIFICO “GIUSEPPE NOVELLO”
INDIRIZZO LINGUISTICO
CLASSE 3^M
DNA CHEMICAL
COMPOSITION
DNA is made up of Nucleotides,
that are really important for living organisms,
as they are the structural components or building blocks of
DNA and RNA
and they control all hereditary characteristics
.
DNA CHEMICAL
COMPOSITION
Each nucleotide contains a
molecule of sugar,a
phosphate group and an
organic base.
The sugar and the
phosphate group are
identical in each
nucleotide, instead the
organic bases are
different.
NUCLEOTIDE’S SUGAR
The 5-carbon sugars ribose and deoxyribose are important
components of nucleotides and are found in RNA and DNA.
The sugars found in nucleic acids are pentose sugars and it has five
carbon atoms.
OH
PHOSPHATE GROUP
Nucleotides can have one, two, or three phosphate groups.
Nucleotides with two or three phosphate groups are good energy
donors. Phosphate groups can also be joined to other molecules,
such as sugar.
NITROGENOUS BASE
Nucleotides in DNA
contain four different
nitrogenous bases:
Thymine(T), Cytosine(C),
Adenine(A) and Guanine(G).
There are two groups of
bases:
Pyrimidines: Cytosine and
Thymine that have a single
six-member ring.
Purines: Guanine and
Adenine which have a double
ring made up of a five-atom
ring attached by one side to
a six-atom ring. These bases
are the part of DNA that
stores information.
DNA’S STRUCTURE
DOUBLE HELIX
Nucleotides are attached
together to form two
long strands that spiral
to create a structure
called a double helix.
THE COMPLEMENTARY OF
BASES
The 'rungs' of the DNA ladder are
each made of two bases, one
base coming from each leg.
The bases connect in the middle:
'A' only pairs with 'T', and
'C'only pairs with 'G'.
The bases are held together
by hydrogen bonds.
DNA FUNCTIONS
Bring information for
the proteins
Transmit genetic
information
BRING INFORMATION FOR THE PROTEINS
The disposition of the 4 bases
(adenine, thymine, guanine and
cytosine) constitutes the
genetic information, that can be
read through the genetic code,
which avoids the translation into
amino acids.
This process is possible just if
there is a molecule of RNA.
TRANSMIT GENETIC INFORMATION
The genetic information is duplicated before the cell division,
by way of DNA replication, that prevents the loss of
information.
The genetic information is trasmitted by the chromosomes.
CHROMOSOMES
• A chromosome is a
packaged and
organized structure
containing most of
the DNA of a living
organism.
• Each chromosomes
is situated in a
particularly part of
the cell, called
nucleus.
The number of chromosomes varies from species to
species:
In the human
body there are
46 chromosomes
RNA’s functions
Ribonucleic acid (RNA) is a molecule implicated in
various biological roles in coding, decoding,
regulation, and expression of genes.
RNA’s structure
In RNA, the sugar is ribose
instead of deoxyribose.
•
In RNA, we can find uracil
instead of thymine.
•
The RNA does not form a
double helix but has the
structure of a simple chain .
•
The three-dimensional
structure of RNA is far more
different than that of the
DNA .
•
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DNA EXTRACTION
FROM A KIWI
Ingredients:
• Kiwi
• Dishwashing liquid
• Salt
• Water
• Ice
• Cold alchool
• Pineapple
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PROCESS 1
Put alchool in ice
(the colder the ethanol is, the greater
the amount of DNA that is
percipitated)
PROCESS 2
Prepare an extraction solution with
-3g of salt
-10ml of dishwashing liquid
-90ml of water
PROCESS 3
Shake slowly to dissolve salt,
without making bubbles
PROCESS 4
Peel the kiwi fruit and chop it into small
chunks, mash them and put the pulp in a
becker
PROCESS 5
Put the becker into hot water (60°C) for
15 minutes
PROCESS 6
After 15 minutes,
you have to cool
and to filter it by
a special paper
PROCESS 7
Gently, pour the
cold alcohol along
the wall of the
tube, with the aim
of forming a
phase above the
filtrate
PROCESS 8
After a few
minutes at the
interface
between the two
phases it will
form a gelatinous
mass: the kiwi’s
DNA
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WHAT HAPPENED?
The cells are composed by robust cell walls,
cell membranes and within the nucleus they
contain DNA and a large number of proteins
The high temperature destroys the cell
walls exposing the cell membranes
The dishwashing liquid dissolves
cell membranes
The salt condenses the DNA, however
given that it is not soluble in alcohol, it
appears as a gelatinous substance at the
interface.