 Basic building block of nucleic acids  Three parts: › 5-Carbon Sugar › Phosphate group › Nitrogen base

 Deoxyribonucleic acid  Double-stranded nucleic acid  D ouble helix shape—like a twisted ladder  Contains genetic information for cell functions, growth, and division.

 Sugar component in the backbone of DNA  5-Carbon sugar

 Binds with sugar in DNA backbone

 Nitrogen base pairs form the “rungs” of the DNA structure.  Adenine › Purine base that pairs with thymine  Thymine › Pyrimidine base that pairs with adenine  Cytosine › Pyrimidine base that pairs with guanine  Guanine › Purine base that pairs with cytosine

 Adenine ALWAYS pairs with Thymine in DNA molecules!!  Cytosine ALWAYS pairs with Guanine!!