2/1/12 Reminder: Pick up science fair boards by Friday afternoon if you want them Objective: Understand the structure of DNA and how base-pairing allows for self-replication Warm-Up: What is the relationship between DNA, a gene, and a chromosome?

DNA structure Deoxyribonucleic acid – one big molecule Made of smaller building blocks called nucleotides Nucleotides have 3 parts Ring-shaped sugar (deoxyribose) Phosphate group Nitrogen base (single or double ring of carbon and nitrogen)

DNA Structure “Backbone” of DNA is made of sugar and phosphate Adenine (A) and guanine (G) have double rings Thymine (T) and Cytosine (C) have single rings Adenine and thymine form a double hydrogen bond Guanine and cytosine form a triple hydrogen bond