2. NUCLEIC ACIDS:
• Are biological molecules essential for known forms of life
on earth
• They include DNA and RNA
• Discovered by Friedrich Miescher in 1869
• They are named so because of their initial discovery in
nucleus
3. DNA stands for deoxyribose nucleic acid
This chemical substance is present in the nucleus
of all cells in all living organisms
DNA controls all the chemical changes which
take place in cells
The kind of cell which is formed is
controlled by DNA
The kind of organism which is produced is
controlled by DNA
DNA 2
4. DNA is a very large molecule made up of a long
chain of sub-units
The sub-units are called nucleotides
Each nucleotide is made up of
a sugar called(Pentose)
a phosphate group -PO4 and
an organic base
DNA molecule 3
5. Ribose is a sugar, with only five carbon atoms
in its molecule
Deoxyribose is almost the same but lacks one
oxygen atom at C2
Both molecules may be represented by the symbol
THE SUGARS:RIBOSE & DEOXYRIBOSE
4
6. The nucleotide bases found in nucleic acids are related either
to the purine or pyrimidine ring system.
Both DNA and RNA contain two major purine bases, adenine (A)
and guanine (G).
In both DNA and RNA one of the Pyrimidines is cytosine (C),
but the second major pyrimidine is not the same in both: it is
thymine (T) in DNA and uracil (U) in RNA.
Organic Bases
7.
8.
9. ROLE OF PHOSPHODIESTER
LINKAGE
• Phosphodiester Bonds Link
Successive Nucleotides in Nucleic
Acids
• Linked through phosphate-group
“bridges,” in which the 5’-
phosphate group of one nucleotide
unit is joined to the 3-hydroxyl
group of the next nucleotide,
creating a phosphodiester linkage .
10. The chain has a 5 end,
which is usually attached
to a phosphate, and a 3
end, which is usually a
free hydroxyl group
11. A molecule of
DNA is formed
by millions of
nucleotides
joined together
in a long chain
PO4
PO4
PO4
PO4
sugar-phosphate
backbone
+ bases
Joined nucleotides 7
16. CENTRAL DOGMA
• The set of ideas that describes how the cell uses the information
stored in DNA is called the Central dogma
• The first step of central dogma is Transcription
• Transcription uses DNA as a template to copy genetic information
into form of RNA
• The second step of central dogma is Translation
• Translation synthesizes the protein using RNA as a template
17. DNA Replication
Process of producing two
identical replicas from one
original DNA molecule.
It occurs with the help of a lot
of enzymes/catalyst.
