1. Have Your DNA and Eat It Too I will be able to describe the structure of the DNA molecule I will be able to explain the rules of base pairing I will understand that information is stored within the DNA molecule in the form of a sequence of chemical bases, (A, T, C, G)

2. DNA Provides the instructions for building and operating ALL living things – DNA Instructions: Divided into segments; genes – Genes: Provide information to make a protein – Protein: Carries out a specific function in the cell

3. DNA Deoxyribonucleic Acid Composed of: – 2 backbones – 4 types of chemical bases

4. Backbone Formed by a chain of alternating phosphates and sugars – Sugar molecule Provides attachment site for one of the chemical bases

5. Chemical Bases Adenine (A) Thymine (T) Cytosine (C) Guanine (G) A pair of bases is connected together by hydrogen bonds – Also connected to a sugar compound; to attach to the backbone Base Pair

6. DNA Molecule Comparable to a twisted ladder – 2 backbones = sides of ladder – Base pairs = rungs (steps) of ladder – Double helix = twisted ladder shape Sequence – Consecutive order of bases on one side (strand) – Complementary order of bases on other side (strand) based on pairing rules A-T and C-G

7. DNA Replication Exact copies of DNA – Allowed because of the matching of base pairs 1.Double helix untwists 2.Two strands separate – Break hydrogen bonds between base pairs 3.Two NEW strands made – Read each side of the original ladder – One step (base) at a time 4.At each step, matching base fills in (with its matching sugar and phosphate) – Completes the rung – Lengthens the new DNA strand When process complete: 2 identical DNA double helixes – Each Double Helix: One original DNA strand One New strand

8. Importance of DNA Replication Part of cell division process – Occurs before a cell divides Interphase – Duplicates DNA – New cell will have SAME genetic information – Exact copies due to base pair matching

9. If all organisms have DNA, how are we different? Structure of DNA molecules is the SAME in ALL living things The diversity of life is the result if differences within the DNA sequence – Different order of A-T and C-G base pairs (the rungs of the ladder go in a different order!)