DNA

• DNA consists of pentose sugars, nitrogenous bases, and phosphate
• pentose sugars for DNA have a H bound to the 2 carbon while RNA have a have an OH
• the nitrogenous bases of DNA are adenine, cytosine, guanine and thymine
• the nitrogenous bases of RNA are adenine, cytosine, guanine, and uracil
• deoxyribose sugars bind to the N9 of purines and the N1 of pyrimidines
• nucleosides are molecules of a sugar and a nitrogenous base where the base binds to the C1 of a deoxyribose
• nucleotides are molecules of nucleosides and phosphates where the phosphate group is attached to the C5 of the deoxyribose sugar
• DNA is a polymer of deoxyribonucleotides
• nucleotide monomers polymerize via phosphodiester bonds
• covalent bonds form between the phosphate and C3 and C5 of two pentose sugars to form the pentose-phosphate backbone
• polynucleotide has polarity with C-5 PO4 and C-3 OH end
• a DNA molecule is negatively charged because of the phosphate group
• adenine and guanine are purines
• cytosine, thymine, and uracil are pyrimidines
• Chargaffs rule states that the % adenine = % thymine, and % cytosine = % guanine
• DNA molecules are cylindrical and 2nm in diameter
• 0.34nm periodicity suggested that bases were stacked like pennies
• x shaped pattern seen in x-ray diffraction studies indicated helical structure
• strands in DNA are antiparallel
• the exterior backbone is hydrophilic while the interior bases are hydrophobic
• hydrogen bonding between bases keeps the two strands in tact
• DNA developed after RNA
• the watson and crick model of DNA stated that it is a helical structure, the bases are hydrophobic, the backbone is hydrophilic , the strands are antiparallel, and purines are based paired with pyrimidines