1. The Structure of DNA
Why do we care about DNA?

2. Nucleic Acid It’s all in the name Nucleotides
DNA stands for DeoxyriboNucleic Acid so it should come as no surprise that DNA is a…
Nucleic Acid
What subunits make up nucleic acids?
Nucleotides

3. The Structure of a Nucleotide
The basic building block of DNA is the structure called a nucleotide.
Nucleotides are made up of three parts.
Nitrogenous
Base
Phosphate
Sugar

4. The Four Bases Adenine Thymine Cytosine Guanine
In DNA there are four different types of nucleotide.
Different nucleotides have different bases.
Adenine
Thymine
Cytosine
Guanine

5. The Four Nucleotides
Purines
Two Rings
Pyrimidines
One Ring

6. DNA is made up of two strands
Each strand of DNA is held together by a sugar-phosphate backbone.
The phosphate of each nucleotide in a strand is attached to the sugar of the nucleotide next to it.

7. The Double Helix
The two strands of DNA are attached at the nitrogenous bases.
The base-pairing rule states that Adenine always pairs with Thymine and Cytosine always pairs with Guanine. A T C G

8. The Double Helix

9. The Double Helix

10. The Double Helix
The two strands of DNA are twisted around each other to form a double spiral or double helix.

11. The Double Helix
The double stranded DNA makes one complete twist for every 10 pairs of bases.
The two strands are pointed in opposite directions

12. DNA Model You will build a model of DNA
It must hang from the ceiling or stand on its own.
The following parts must be included:
deoxyribose sugar, phosphate group, adenine, thymine, guanine, cytosine,
covalent bonds and hydrogen bonds.
No perishable materials and no kits

13. DNA Model
The DNA must be twisted and must be at least 10 base pairs long, making a complete twist.
A key must be included or the parts must be clearly labeled.
You may work with one other person, but you must inform me by Friday Feb 19th
The project is worth 30 points and is due on Tuesday March 1st.

14. DNA Grading Sugars labeled - 4 points _____
Phosphate labeled - 4 points _____
Bases labeled points_____
Covalent bonds points_____
Hydrogen bonds points _____
Directional strands – 2 points ____
Complete twist points _____
Correct structure points _____
Creativity points _____