1.
DNA
And its Replication
Not in text

2.
DNA stands for deoxyribonucleic
acid.
Double helix model proposed by
James Watson and Francis Crick in
1953.

3.
Shape is double helix, like a
twisted ladder.
DNA is composed of subunits
called nucleotides.

4.
A nucleotide includes:
1 molecule of the sugar
deoxyribose
1 phosphate group, and
1 of four nitrogen bases
deoxyribose

5.
The four nitrogen bases are:
Adenine – A
Thymine – T
Guanine – G
Cytosine - C

6.
Thymine and cytosine are single
ringed bases called pyrimidines.
Guanine and adenine are double
ringed bases called purines.

7.
The rungs of the ladder are held
together by the weak hydrogen
bond formed between a
pyrimidine and a purine base.
This bond is easily broken and
reformed for DNA replication and
RNA synthesis.

8.
BASE PAIRING RULE
Adenine - Thymine
Guanine - Cytosine
These nitrogen bases always bond
together.

9.
DNA Replication
Process of copying DNA in the
nucleus.
Following DNA replication, two
identical DNA molecules have been
produced from a single double-
stranded DNA molecule.

10.
This process is
“semiconservative” in that each
strand of the original double-
stranded DNA molecule serves as
template for the reproduction of
the complementary strand.