1. Structure and Replication
DNA
Structure and Replication
DNA Rap Song

2. Student Expectations
B 6.A1
Identify components of DNA.

3. DNA Structure DNA stands for Deoxyribonucleic Acid Shape: Double helix
Monomers: Nucleotides (has 3 parts)
Sugar, (deoxyribose),
phosphate
nitrogenous base
Bases are held together by hydrogen bonds.

4. Four Nitrogenous Bases
Adenine (A)
Guanine (G)
Cytosine (C)
Thymine (T)
Purines (double ring) Adenine and Guanine
Pyrimidines (single ring) – Cytosine and Thymine
Chargaff’s rule:
Adenine pairs with thymine. A –T T – A
Guanine pairs with cytosine. G – C C – G

5. Nucleotides: Purines Pyrimidines Phosphate group Sugar: Deoxyribose
Adenine
Guanine
Thymine
Cytosine
Cytosine
Thymine
Phosphate group
Sugar:
Deoxyribose

6. Build a DNA molecule

7. A Closer Look at DNA: Page 294
Nucleotide
Hydrogen bonds
Sugar-phosphate backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)

8. A closer look at DNA: How DNA condenses
Chromosome
Centromere
Supercoils
DNA
double
helix
Histones
Chromatin

9. Student Expectation B 5.A1
Describe the stages of the cell cycle, including deoxyribonucleic acid (DNA) replication.

10. What is Replication?
The process of copying DNA during S phase of interphase in the nucleus
Makes sure that a daughter cell will have a complete set of chromosomes
Original strand of DNA serves as a template for 2 new strands
Template: a pattern; an original model
Each new strand will be identical to the original strand because of Chargaff’s rule.

11. How does replication work?
1) Helicase unwinds the double helix, forming a “replication fork,” where replication takes place
2) DNA polymerase bonds the necessary nucleotides to the original DNA strand to complete 2 new DNA molecules
3) DNA polymerase also “proofreads” the new DNA strand to make sure it is an exact copy of the original DNA

12. DNA Replication Facts:
DNA polymerase can only work in one direction so:
2 new strands of DNA are made in opposite directions
One strand is made in sequence of nucleotides
The other strand is what we call the “lagging strand” because nucleotides are added in fragments

13. DNA Replication: Page 298 Original strand DNA polymerase New strand
Growth
Growth
Replication fork
Replication
fork
Nitrogenous
bases
New strand
Original strand

14. Videos http://www.youtube.com/watch?NR=1&feature=fvwp&v=bW5JnYZImJA