2. DNA: The Code of Life Biology

3. I. What is DNA? DNA stores our genetic code in the nucleus the information is passed from one generation to the next (from parent to offspring)

4.  DNA is a double helix  There are 3 meters of DNA in each nucleus  DNA is tightly wound to fit in the nucleus

5. II. Structure of DNA Nucleotides are made of 3 things: 1. Sugar (deoxyribose) 2. Phosphate 3. Bases—either Adenine, Thymine, Cytosine, or Guanine

8. DNA Replication DNA unzips to replicate (copy itself) Helicase is the enzyme used in this process

9. New nucleotides are added to both sides of unzipped strand using DNA polymerase Replication is semi- conservative: the new DNA has one strand of old and one strand of new

11. WHY REPLICATE? (DNA MAKING A COPY OF ITSELF)?????  To make new cells (mitosis)!  For example:  Cells wear out and die and need replacing  new cells needed as organism forms (grows from an embryo)  Children grow into adulthood