DNA is a double-stranded helical molecule found in cell nuclei that provides instructions for protein synthesis by replicating itself before cell division. It is composed of nucleotides, each containing a nitrogen base (adenine, guanine, cytosine, thymine, or uracil), a pentose sugar, and a phosphate group, arranged in a double helix structure.

1. Intro to DNA

2. Nucleic Acids Composed of carbon, oxygen, hydrogen, nitrogen, and phosphorus Their structural unit, the nucleotide, is composed of N-containing base, a pentose sugar, and a phosphate group

3. Nucleic Acids Five nitrogen bases contribute to nucleotide structure – adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U) Two major classes – DNA and RNA

4. Deoxyribonucleic Acid (DNA) Double-stranded helical molecule found in the nucleus of the cell Replicates itself before the cell divides, ensuring genetic continuity Provides instructions for protein synthesis

5. Structure of DNA Figure 2.22a

6. Structure of DNA Figure 2.22b