2. 3 parts of a Nucleotide A ring-shaped sugar called deoxyribose
A phosphate group
A nitrogenous base – this group makes nucleotides unique from one another

3. Nitrogenous Bases
Purines – two rings
Pyrimidines – one ring

4. DNA Structure - Double Helix
Nucleotides are joined together by covalent bonds that connect the sugar of one nucleotide to the phosphate group of the next.
Sugar-phosphate backbones on the outside

5. Hydrogen bonds form between bases that are across from one another in the double helix
Bases on the inside

6. Pairing A (Adenine) pairs with T (Thymine)
G (Guanine) pairs with C (Cytosine)

7. The DNA Structure Lets make our own complimentary strand.
Sample Strand:
A T G A C A T C C C A A
Complementary Strand is:

8. The DNA Structure Lets make our own complimentary strand.
Sample Strand:
A T G A C A T C C C A A
Check your answer:
T A C T G T A G G G T T

9. Write the complementary strand
ATGTCCGAT
TACAGGCTA
CATGGCTTA
GTACCGAAT

10. DNA Replication
The strand that is copied to form a new strand is called a template
In replication of a double-stranded DNA, both original (parental) DNA strands are copied

11. DNA Replication: Step 1 2 nucleotide chains are separated.
Replication fork.
Chains are separated by an enzyme called a helicase which breaks hydrogen bonds.

12. DNA Replication: Step 2
DNA polymerase binds to the separated chains of DNA. As it moves down the chain new chains of DNA are assembled using complementary nucleotides.

13. When copying is finished, you have two separate helices, each consist of one of the original strands plus its copy.

14. Question 1
From the template below, write the complement.
GCTTTAGTAC

15. Question 2 You have a strand of DNA. 25% of it is thymine.
What percent is:
Adenine?
Guanine?
Cytosine?

16. Question 3 You have a strand of DNA. 10% of it is thymine.
What percent is:
Adenine?
Guanine?
Cytosine?

17. Homework Due tomorrow: Paper pets questions.
Read `Print and complete study guide due on Wednesday.