1. DNA
Structure

2. DNA Overview

3. DNA Structure
DNA consists of two strands that are arranged into a ladder-like structure called a Double Helix.
A molecule of DNA is made up of millions of monomers called Nucleotides.
Each nucleotide consists of:
Phosphate group
Pentose sugar
Nitrogenous base

4. Nucleotides
Phosphate
Nitrogenous
Base
Pentose
Sugar

5. The phosphate and sugar form the backbone of the DNA molecule, whereas the bases form the “rungs”.
There are four types of nitrogenous bases.

6. Nucleotides A
Adenine T
Thymine C
Cytosine G
Guanine

7. Chargraff’s Rule:
Each base will only bond with one other specific base. This is called complementary base pairing.
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
Form a base pair.
Form a base pair.

9. Thymine and Cytosine are pyrimidines
Thymine and cytosine each have one ring of carbon and nitrogen atoms. C N O
Cytosine C N O
Thymine

10. Adenine and Guanine are purines
Adenine and guanine each have two rings of carbon and nitrogen atoms. C N O C N
Adenine
Guanine

11. DNA Structure A gene is a section of DNA that codes for a protein.
Each unique gene has a unique sequence of bases.
This unique sequence of bases will code for the production of a unique protein.
It is these proteins and combination of proteins that give us a unique phenotype.

12. DNA
Gene
Protein
Trait