2. DNA is the hereditary
The deoxyribonucleic acid,
material in humans and
DNA, is a long chain of almost all other organisms.
nucleotides which consist of: Most DNA is located in the
• Deoxyribose (a pentose cell nucleus , but a small
= sugar with 5 carbons) amount of DNA can also be
• Phosphoric Acid found in the mitochondria
• Organic (nitrogenous) (where it is called
bases (Purines - Adenine mitochondrial DNA or
and Guanine, or mtDNA).
Pyrimidines -Cytosine The information in DNA is stored
and Thymine) as a code made up of four
chemical bases
3. • Rosalind Franklin used
X-ray diffraction to
understand the
physical structure of
the DNA molecule.
• The structure of
double helix was first
described by James
Watson and Francis
Crick in 1953.
4. Purines Pyrimidines
A T
G C
• four chemical bases:
adenine (A), guanine (G),
cytosine (C), and
thymine (T).
• DNA bases pair up with
each other, A with T and
C with G, to form units
called base
pairs.
The pyrimidine bases have a 6-
membered ring with two nitrogens
and four carbons.
The purine bases have a 9-membere
double-ring system with four
nitrogens and five carbons.
5. • Together, a base, sugar, and phosphate are
called a nucleotide.
• Nucleotides are arranged in two long
strands that form a spiral called a double
helix.
• The structure of the double helix is
somewhat like a ladder, with the
base pairs forming the ladder’s
rungs and the sugar and phosphate
molecules forming the vertical
sidepieces of the ladder.
6. • DNA stores an organism's genetic
information and controls the
production of proteins.
DNA's function is to provide
the code on which all life is
based.
DNA is found primarily in the nucleus of a
cell in strands of genetic material called
Chromosomes.
Each chromosome is a single piece
of double stranded DNA.
