Related: BCMB 412 Advanced Molecular Biology and Genomics
DNA nucleotides are one of four bases (Adenine, Guanine, Cytosine, and Thymine) attached to deoxyribose sugars through glycosidic bonds.
Phosphodiester bods = nucleotides joining with each other
The nucleotides join into polynucleotide chains via phosphodiester bonds. Phosphate groups connect the C3 of one nucleotide’s deoxyribose to the C5 of the next.
This creates the iconic directional chain with a 5’ phosphate end on one side and a 3’ hydroxyl end on the other. Important for primers!
Chargaff used paper chromatography to show that nucleotide ratios varied between species but the ratios of A:T and G:C consistently equaled 1.
Glycosidic bonds = nucleotides/sides to ribose sugar
Nucleotides are divided into puries (A,G) and pyrimidines (C,T), with purines bonding from their N9 and pyrimidines from their N1 to the sugar’s C1.
A glycosidic bond connects the nitrogenous base (A, G, C, T) to deoxyribose, forming a nucleoside. When a nucleoside is phosphorylated at the C5 position of the deoxyribose, it becomes a nucleotide.