1. DNA Structure Notes QQ#1: What do you know about the structure of DNA?
Be as detailed as Possible

2. Deoxyribose Nucleic Acid: Structure Notes
Called a double helix (a spiral ladder)

3. DNA is a Polymer QQ#2 What are the three parts of the nucleotide?
DNA’s Monomers:
repeating subunits called NUCLEOTIDES
Nucleotides consist of three parts:
Phosphate Group
Sugar Group
Nitrogenous Base
QQ#2
What are the three parts of the nucleotide?

4. Nucleotide Structure Copy the Diagram In your notes:
The phosphate bonds to what is called the 5’ (five prime) carbon of the sugar molecule.
The base bonds with the sugar at the 1’ carbon.
Can be one of four bases:
Adenine, Thymine, Cytosine, Guanine
Discuss: How do you think these may link together to form a polymer?

5. Nucleotides are repeating Subunits

6. QQ#3
Draw a visual to represent two nucleotides bonding together

7. DNA’s Repeating Structure
DNA is directional
The nucleotides are connected together by a phosphodiester bond between phosphate groups at the 3’ and 5’ carbon on the the sugar molecule.
These bonds create one side of the strand of DNA.
The other (complementary) strand runs in the opposite direction connected in the middle by the bases
called anti-parallel chain

8. Bases In general Categories of Bases pyrimidines – one ring
bases can accept hydrogen ions or more generally, donate a pair of valence electrons when bonding
The opposite of an acid
Categories of Bases
pyrimidines – one ring
Cytosine and Thymine
purines – two rings
Adenine and Guanine

9. QQ#4:
Can you think of a way to remember which bases are purines and which are pyrimidines?
Categories of Bases
pyrimidines – one ring
Cytosine and Thymine
purines – two rings
Adenine and Guanine

10. Hydrogen Bonds A Purine always bonds with a Pyrimidine
Bases are connected across middle of helix:
Adenine forms (2) h-bonds with Thymine
Guanine forms (3) h-bonds with Cytosine
These bonds hold the two strands of DNA together and cause the twisting to occur

11. Within the helix there is a major and minor groove
The entire code that instructs our cells depends on the order of Adenine, Guanine, Thymine, Cytosine
The specific bonding
angles of the
nucleotides forces
the helix shape.
Within the helix there is a major and minor groove

12. Major and Minor Grooves
Caused by bonding angles
Major groove allows proteins to bond: important for replication.
Each full twist of the helix has 10 nucleotides

13. Putting it All together

14. Exit Slip
On a separate scratch piece of paper, answer the following questions.
1. What do you know now about DNA structure?
2. Compare this knowledge with what you knew before?
3. Why is the structure of DNA important to the essential questions: In what way(s) does your DNA define you?
4. Predict how the structure of DNA relates to how all organisms have the same exact DNA in all cells

15. Your Model
You may create a model with our without the major and minor grooves. All other components of DNA structure must be included for accuracy