1. DNA Replication
Goal: Students will be able to summarize the events of DNA replication.

2. Structure: DNA Length DNA molecules are very long.
The nucleus of a human cell contains more than 1 meter (3 feet) of DNA.
DNA must be folded and coiled in order to fit in such a small space.

3. Chromosome
Supercoils
Coils
Nucleosome
Histones
DNA
double
helix

4. DNA Structure Chromosomes are made of DNA.
The DNA is wound around proteins called Histones. (like thread around a spool)
When chromosomes are unraveled, the DNA strands are called Chromatin.

6. Structure: DNA DNA is a double helix
Two strands of nucleotides wound around each other like a twisted ladder
Nitrogen bases of opposite strands held together by Hydrogen bonds.
Sugar-Phosphate Backbone held together by Covalent bonds.

7. Sugar-phosphate backbone Covalent Bonds
Hydrogen bonds
Nucleotide
Sugar-phosphate backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
Covalent Bonds

8. Structure: Base Pairing
DNA strands are made of nucleotides
Phosphate group
Deoxyribose sugar
Nitrogen Base (G, C, A, or T)
Purines bond to Pyrimidines
A = T
G = C

9. Structure: Nitrogenous Bases
Double ring PURINES
Adenine (A)
Guanine (G)
Single ring PYRIMIDINES
Thymine (T)
Cytosine (C)
A or G
T or C
copyright cmassengale

10. DNA replication PURPOSE
Every cell in your body has the SAME DNA
DNA has to be copied before a cell divides
DNA is copied during interphase
New cells will need identical DNA strands

11. DNA replication PURPOSE
DNA replication is SEMI-CONSERVATIVE. Each daughter molecule of DNA is made of ONE ORIGINAL strand and ONE NEW strand.

12. Summary of DNA Replication
Helicase (an enzyme) breaks the Hydrogen bonds between the nitrogen bases and separates (unzips) the original strands of DNA.
DNA polymerase (another enzyme) bonds complimentary DNA nucleotide bases to each original strand. (G=C, A=T)
DNA polymerase then proofreads the DNA for mistakes (mutations).

13. DNA replication BIG IDEA
Each strand serves as a template for the attachment of complimentary bases.
G = C, A = T

14. DNA replication BIG IDEA
Base Pairing ensures that when
DNA is replicated, you get
2 identical copies of DNA
each with ONE NEW STRAND and
ONE ORIGINAL STRAND!