1. DNA History Function Structure Replication

2. History - Structure Erwin Chargaff –1950’s Discovered that the amount of A is always equal to the amount of T. –The amount of C is always equal to the amount of G. –What can be inferred? A goes with T G goes with C –This became known as Chargaff’s Rule Rosalind Franklin 1950’s she used x-ray diffraction to take a “photo” of DNA. Watson & Crick 1953 Using their own research and other the created a model of DNA.1953 Using their own research and other the created a model of DNA. DNA described as Double Helix or twisted ladder.DNA described as Double Helix or twisted ladder.

3. FUNCTION Direct Cells Activities Genes, a segment of DNA codes for a certain protein. For example the Gene for making Insulin (protein) is coded for in a section of DNA. The Gene has to be read and pass on the information to the ribosome. DNA RNA PROTIEN

4. STRUCTURE  DNA is a double helix or a twisted ladder.  Both sides of the ladder are made of sugar and phosphate.  The RUNGS (steps) are the bases  Rungs  Adenine pairs with Thymine  Cytosine pairs with Guanine *They complement each other.  The bases are complementary, meaning they fit together. Only A with T and C with G. MORE

5. BUILDING BLOCKS OF DNA.  DNA is like a puzzle where only certain pieces of the puzzle fit together.  Each puzzle piece is called NUCLEOTIDE.  Each puzzle piece is made of a:  SUGAR,  PHOSPHATE  NITROGEN BASE. 4 Bases  Adenine  Thymine  Cytosine  Guanine

6. Replication o Purpose is to make an exact copy of the DNA molecule. o Why? o So during cell division (mitosis) each new cell has an exact copy of the original. STEPS OF REPLICATION: 1.Enzyme (polymerase) UNZIPS the DNA at the weak hydrogen bonds. 2.Free floating nucleotides of DNA BOND to the single strand by BASE PAIRING. 3.Another enzyme rezips the two chains together. FINAL PRODUCT A total of 4 strands in groups of two.