DNA

• double helix - shape of DNA due to coiling of two sugar-phosphate backbones into a spiral
• nucleotide - five carbon sugar, phosphate group and a nitrogenous base
• nucleic acid - acidic molecule found in the nucleus
• deoxyribose - five carbon sugar from ribose by replacing a hydroxyl group with hydrogen
• purine - adenine or guanine (larger two ring structure)
• pyrimidine - thymine or cytosine (smaller one ring structure)
• nucleotide - linked by covalent bonds in condensation reactions

  
• in DNA, pentose sugar is deoxyribose
• when nucleotides contain more than one phosphate group, they become phosphorylated nucleotides
• the bond between pentose sugar and phosphate group is a phosphodiester bond
• adenine and thymine pair with two hydrogen bonds
• guanine and cytosine pair with three hydrogen bonds
• antiparallel sugar-phosphate backbones - upright part of large DNA molecule that resembles a ladder is formed by the sugar-phosphate backbones of the antiparallel polynucleotide strands. 'opposite directions' of the two strands refers to the direction that the third and fifth carbon molecules on the five-carbon sugar, deoxyribose, are facing.
• adenine becomes adenosine when it is phosphorylated
• guanine becomes guanosine when it is phosphorylated
• cytosine becomes cytidine when it is phosphorylated
• thymine becomes thymidine when it is phosphorylated
• a phosphodiester bond is a covalent linkage between the hydroxyl (OH) group attached to the 3' carbon of deoxyribose sugar and the phosphate of an adjacent nucleotide
• stores genetic information