1. 8.2 Structure of DNA KEY CONCEPT DNA structure is the same in all organisms.

2. 8.2 Structure of DNA DNA is the molecule of Life Deoxyribonucleic Acid Contains genetic information for cell functions, growth, and division Shape – Double Helix Watson & Crick – Discovered the shape of DNA

3. 8.2 Structure of DNA DNA is made up of a long chain of nucleotides. Each nucleotide has three parts. –a phosphate group –a deoxyribose sugar –a nitrogen-containing base phosphate group deoxyribose (sugar) nitrogen-containing base

4. 8.2 Structure of DNA -Adenine -Thymine -Cytosine-Guanine DNA is composed of four types of nucleotides.

5. 8.2 Structure of DNA Watson and Crick determined the three- dimensional structure of DNA by building models. DNA is a double helix that is made up of a sugar- phosphate backbone on the outside with bases on the inside.

6. 8.2 Structure of DNA T A C G Nucleotides always pair in the same way. The base-pairing rules show how nucleotides always pair up in DNA. – A pairs with T – C pairs with G

7. 8.2 Structure of DNA The backbone is connected by covalent bonds. hydrogen bond covalent bond The bases are connected by hydrogen bonds.

8. 8.2 Structure of DNA DNA Replication – Replication = DNA making copies of itself –DNA must be copied before a cell can divide –Each new cell will have a complete set of DNA

9. 8.2 Structure of DNA DNA Replication: Process Replication begins when the enzyme DNA helicase opens the DNA forming replication bubbles

10. 8.2 Structure of DNA DNA Replication- The Big Picture Each Bubble has 2 Forks – each fork has a leading and lagging strand

11. 8.2 Structure of DNA DNA Replication – DNA Polymerase The enzyme DNA polymerase brings new nucleotides to the replication fork - it pairs them according to base pairing rules A pairs with T C pairs with G

12. 8.2 Structure of DNA DNA Replication The process continues until 2 complete copies of the DNA are produced Each copy of the DNA contains one strand of DNA from the original DNA molecule and one new strand that was produced by replication Known as semi-conservative replication