1. I. DNA

2. Deoxyribonucleic Acid
Carries all heredity information
Gene: segment of DNA that controls the production of a specific protein

3. D. Nucleotide: subunit of DNA
Composed of –
Sugar: deoxyribose
Phosphate
Nitrogen base:
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)

4. Shape: Double helix (twisted ladder)
Sides of ladder: Sugar  Phosphate
Rungs: Pair of Nitrogen bases
Paired bases:
Adenine – Thymine
Guanine – Cytosine
Hydrogen Bonds between bases
-5’-3’strands line up opposite
each other.

8. II. Nitrogen Bases: Two Groups: Purines: A and G Pyrimidines: C, T, U
c. Purine base always binds to pyrimidine base

9. III. DNA Replication
Semiconservative Replication (one parent DNA splits to become two new identical DNA)
Hydrogen bonds break
(DNA polymerase)
Free nucleotides pair w/ complementary base pairs
2 strands of identical DNA
are created
An enzyme called DNA polymerase breaks the H bonds between nucleotides

10. DNA Replication (cont’d)
DNA polymerase (enzyme):
Adds appropriate nucleotides to the new DNA strand (3’ end).
-Leading strand: elongates as DNA unwinds (5’-3’ direction)
-Lagging strand: elongates away from replication fork and synthesized discontinuously into Okazaki fragments
-small segments of DNA that are later connected by DNA ligase.