Friedrich Miescher isolated nuclein from white blood cell nuclei in 1868, which showed acidic properties and was renamed nucleic acid. Nucleic acids are present in all living cells and viruses, containing the genetic blueprint and instructions for growth, development, and reproduction. There are two main types: DNA containing deoxyribose and the bases A, G, T, C; and RNA containing ribose and the bases A, G, U, C. Nucleic acids are made up of nucleotides containing a phosphate group, sugar, and nitrogenous base. DNA has a double-stranded structure with bases pairing via hydrogen bonds, while RNA is single-stranded.

1. Chapter # 21
XII FDC Prepared by: Sidra Javed

2. Prepared by: Sidra Javed

3. Friedreik Miescher
 Isolated a substance
called Nuclein from
the Nuclei of puss
cells 1868
 Nuclein showed acidic
properties so it was
named Nucleic Acid
 Found Nucleic acids in
sperm heads in 1872
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4. Nucleic Acids are present in:
 Every Living cells as well as Viruses
 Essential substance of genes
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5. Properties
 Contains the Blue-
prints for the normal
growth and
development of
organism
 Able to reproduce,
store and transmit
genetic information
 Undergo mutation
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6. Types
 Deoxyribonucleic
Acids (DNA)
 Ribonucleic Acid
(RNA)
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7. Nucleic Acid and Protein
 Nucleic acid occur as
part of the
conjugated protein –
Nucleoproteins
 Direct the synthesis
of proteins
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8. Structure of DNA and RNA
 Nucleic acids are polymer of nucleotides.
 All nucleotides contain the following three
groups:
 In DNA the sugar is deoxyribose, whereas in
RNA the sugar is ribose.
a phosphate
group
a pentose
sugar
a nitrogen-
containing base
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9. Deoxyribose vs. Ribose Sugar
 Contains one less oxygen atom.
 Carbon-2 contains two H atoms instead of one
H and one OH as in Ribose sugar.
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10. Nitrogenous Bases
 There are five bases split in two types.
 DNA contains A, G, T and C whereas RNA
contains A, G, U and C
 adenine (A) and
guanine (G) are
purine bases.
A G
 thymine (T),
cytosine (C) and
uracil (U) are
pyrimidine bases.
T UC
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11. The Sugar phosphate backbone
 The nucleotides are all
orientated in the same
direction
 The phosphate group
joins the 3rd Carbon of
one sugar to the 5th
Carbon of the next in line.
P
P
P
P
P
P
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12. Adding in the bases
 The bases are
attached to the 1st
Carbon
 Their order is
important
It determines the
genetic information of
the molecule
P
P
P
P
P
P
G
C
C
A
T
T
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13. DNA – Double Stranded
 Each base is paired with a specific partner:
A is always paired with T via Double bond
G is always paired with C via Triple bond
(Purine with Pyrimidine)
 The bases are joined by hydrogen bonds,
individually weak but collectively strong
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14. DNA
P
P
P
P
P
P
C
G
G
T
A
A
P
P
P
P
P
P
G
C
C
A
T
T
Hydrogen bonds
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15. DNA vs. RNA
DNA
-Store the information
-Deoxyribose Sugar
-Nitrogenouse bases are A, C,
G and T
-Double stranded structure
RNA
-Transfer the information
-Ribose Sugar
-Nitrogenous bases are A , C ,
G and U
-Single stranded structure
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