Download 3.3 DNA structure

3.3.1 DNA Structure
DNA is a polymer of Nucleotides
1. Sugar (5C)
2. Phosphate Group (C-5)
3. Nitrogenous Base (C-1)
1. Adenine (A)
Phosphate
Nitrogenous
Base
Pentose
Sugar
2. Guanine (G)
3. Cytosine (C)
4. Thymine (T)
5. Uracil (U)
2 alternatives
H
Deoxyribose
(DNA)
Ribose
(RNA)
3.3.2 DNA Structure: Nitrogenous Bases
1. Adenine (A)
Phosphate
Nitrogenous
Base
Pentose
Sugar
2. Guanine (G)
3. Cytosine (C)
DNA
4. Thymine (T)
5. Uracil (U)
RNA
3.3.3 DNA Structure
The nucleotides within each strand are joined
by covalent bonds.
Alternating sugar and phosphate molecules
form a backbone for each strand.
The phosphate and sugar form the backbone
of the DNA molecule, whereas the bases form
rungs
backbone
the “rungs”.
3.3.4 DNA Structure

The two strands are held together by hydrogen bonds between the
nitrogenous bases.

Each Nitrogenous base will only bond with one other specific base.

Because of this complementary base pairing, the order of the bases in one strand
determines the order of the bases in the other strand.
3.3.5 DNA Structure
Journey into DNA
What is DNA?